tRA: Because you pitched better, and you deserve better.
Have you ever watched a pitcher pitch a game, and walk out with an ERA of like 6, and you said to yourself "He did not pitch all that badly, what on earth happened there?" You figure he let a couple baserunners on via walk, struck out a good number, only sprayed a few singles, how on earth did he let 5 runs cross?
Well, we turn to FIP then, a pitching metric I introduced in an earlier Counting Rocks, which accounts for the elements of a game that a pitcher directly impacts, strikeouts, walks, and home runs. It's a pretty simple formula, I can do the math on my phone calculator.
Based on ERA, K9, BB9, HR9, and FIP, here are the pitchers we've played this season:
|
Name |
K/9 |
BB/9 |
K/BB |
HR/9 |
ERA |
FIP |
|
Randy Flores |
6.75 |
0.00 |
1.00 |
0.00 |
0.00 |
1.72 |
|
Jason Grilli |
11.57 |
3.86 |
3.00 |
0.64 |
2.57 |
2.86 |
|
Jorge de la Rosa |
9.49 |
3.38 |
2.81 |
0.42 |
3.16 |
2.99 |
|
Matt Daley |
7.27 |
4.15 |
1.75 |
0.00 |
4.15 |
3.34 |
|
Manny Corpas |
5.40 |
1.62 |
3.33 |
0.54 |
7.02 |
3.34 |
|
Ubaldo Jimenez |
8.02 |
4.50 |
1.78 |
0.20 |
4.30 |
3.55 |
|
Huston Street |
9.92 |
1.65 |
6.00 |
1.65 |
3.86 |
3.96 |
|
Glendon Rusch |
6.27 |
1.45 |
4.33 |
1.45 |
6.75 |
4.40 |
|
League Average |
7.06 |
3.85 |
1.83 |
1.00 |
4.46 |
4.46 |
|
Jason Marquis |
3.91 |
3.06 |
1.28 |
0.85 |
4.75 |
4.60 |
|
Ryan Speier |
3.18 |
4.76 |
0.67 |
0.00 |
4.76 |
4.63 |
|
Jason Hammel |
5.68 |
2.84 |
2.00 |
1.42 |
4.62 |
5.08 |
|
Aaron Cook |
4.61 |
4.39 |
1.05 |
1.54 |
5.71 |
5.88 |
|
Alan Embree |
4.09 |
4.09 |
1.00 |
1.64 |
4.91 |
6.04 |
|
Franklin Morales |
10.13 |
1.13 |
9.00 |
3.38 |
3.38 |
6.22 |
|
Matt Belisle |
5.28 |
1.76 |
3.00 |
2.35 |
7.63 |
6.22 |
Now just looking at these numbers, we could say "But Glendon Rusch had a below-league-average FIP, why would we let him go?!" Well, the pure stats guy might say that his FIP says he's good, and just make the assumption that defense let him down, BABIP screwed him, etc etc. But we all know that Rusch was a very hittable pitcher this year, despite his good K rate and low BB rate. How hittable though? Did he really deserve that ERA?
The problem is that a pitcher really can control more than just his K's, BB's, and HRs, but to a lesser extent than those 3 true outcomes. FIP still has a lot of use in looking at the more fundamental aspects of what a pitcher does, but it might not be the fairest indicator of a pitchers' performance.
So FIP clearly doesn't have all the answers. If it did, Manny Corpas would still be a downright solid pitcher for us, and Franklin Morales would be in the Springs still. Leaving a ball up in the zone is most definitely controllable by a pitcher, and while the end result is a far more variable event than a "true outcome," it's pretty obvious that the hittable pitchers are going to give up more runs than the not-as-hittable ones.
Because that variability is still going to be a factor in ERA, I still think that it's an inadequate measure of a pitcher's performance in a game. For example, Jason Hammel got more or less screwed by poor defense on Tuesday night, but it's not as if every ball in play past the Barmes error was an error as well. So all the runs were unearned, but as jrockies and Silverblood were commenting, some runs were more unearned than others.
The problem with ERA is that some pitchers are being rewarded or punished for events that aren't their faults. Should we say "good job Marquis" of Dexter dives for a blooper and makes the final out with the bases jacked? Should we curse Alan Embree if he gives up a similar blooper that falls between the two fielders? Probably not. ERA seems to almost be a team statistic, because a run that isn't a home run will involve the team rather than just the pitcher alone. Aaron Cook's runs and outs will come differently than those from Jorge De La Rosa, based on how they pitch and how the team reacts to how they pitch.
There needs to be a "should have been" ERA so we can compare what he actually did and what actually happened.
Welcome to tRA.
Join me after the jump and we'll get into it.
tRA was formulated by Graham MacAree, who is a writer for the SBNation blog Lookout Landing and a moderator at USS Mariner.
tRA is based on the concepts that wOBA is based on. Each offensive event is worth a certain amount of runs, and each defensive event is worth a certain numbers of outs. Tom Tango gave us this data by poring through years of game data and determined how many outs and how many runs occurred after each event. He also formulated how many runs each base/out situation was worth. Using that matrix there will give you a good idea on what run expectancies you should anticipate based on how many are on and how many outs are remaining.
For example, a strikeout is worth 1 out. A home run is worth 0 outs. But how many outs is, say, a fly ball worth? Based on 2008 data, a fly ball (to the outfield) resulted in an out 83% of the time, so we can infer that an outfield fly ball is worth 0.83 outs. However, just because an OFB is worth 0.83 outs does not mean that it's worth 0.17 runs. An OFB, in fact, is worth only 0.046 runs.
So now that we've established that each play is worth a certain number of runs and outs, we can go from there to begin to calculate the tRA.
Using the expected number of runs that a pitcher gives up, based on the run expectancies, and the number of expected outs the pitcher records, we can calculate an analogue to ERA by taking the expected number of runs per expected out (runs/outs) and multiply by 27.
So you're thinking "well that's great, you found ERA again" - and I don't blame you. But here's the thing about tRA that makes it great - it puts the pitcher in a neutral environment (because there are many park-adjustment factors to account for), and puts a neutral defense behind them (because all the run/out expectancies are based on the entire league's performances, so therefore it displays as an average rating), and rather than being the report card for how many runs the team gives up during a pitcher's outing, it actually rates the pitcher on what they let happen.
So similar to FIP, tRA is good as an indicator of how lucky/unlucky a pitcher is getting, in terms of bad defense, bloops, etc etc. But this time, we're not just nullifying hits, but rather, we're accounting for everything that happens, and giving credit to the pitcher for everything he does during the game. It's a better report card of what happened during a pitcher's outing.
So let's look at what tRA means to some of the Rockies' pitchers.
|
Name |
ERA |
FIP |
tRA |
|
Aaron Cook |
5.71 |
5.88 |
6.42 |
|
Alan Embree |
4.91 |
6.04 |
7.65 |
|
Franklin Morales |
3.38 |
6.22 |
4.57 |
|
Glendon Rusch |
6.75 |
4.40 |
4.73 |
|
Huston Street |
3.86 |
3.96 |
2.81 |
|
Jason Grilli |
2.57 |
2.86 |
2.73 |
|
Jason Hammel |
4.62 |
5.08 |
6.38 |
|
Jason Marquis |
4.75 |
4.60 |
4.70 |
|
Jorge de la Rosa |
3.16 |
2.99 |
2.88 |
|
Manny Corpas |
7.02 |
3.34 |
3.36 |
|
Matt Belisle |
7.63 |
6.22 |
5.26 |
|
Matt Daley |
4.15 |
3.34 |
1.85 |
|
Randy Flores |
0.00 |
1.72 |
5.28 |
|
Ryan Speier |
4.76 |
4.63 |
5.20 |
|
Ubaldo Jimenez |
4.30 |
3.55 |
3.47 |
Again, what does this all mean?
Well, the thought is that while Ubaldo Jimenez is sporting a decent 4.30 ERA, were he pitching for the Neutral Planet Neutrals in Neutral Park with Neutral Defense behind him and the Neutral Neutralities batting against him, he'd have a 3.47 ERA. What Ubaldo has allowed to happen through his pitching will allow 3.47 runs per 27 outs. You'll also notice that tRA thinks Matt Daley is a stud so far, and it further solidifies the excellent start that Jorge De La Rosa has had.
So what this breaks down to is we've quantified the concept of "the box score may not show it, but [Pitcher] pitched a solid game".
How can we use it going forward? When we see a pitcher go through some struggles, we can still look at his tRA and see how it corresponds with his FIP and his ERA. We can now say "well, what he's done would give him an ERA of X.XX, but instead he actually has an ERA of Y.YY" and then we can all shake our hands miserably at the defense or the BABIP or whatever we want to blame.
tRA and wOBA won't ever be as easy to use as FIP and OPS, just because they involve a spreadsheet or internet access to get a handle on, while FIP or OPS can be eyeballed or at least figured out on that cheesy calculator in your cellphone. However, with the extra effort, they are numbers that can be taken more at face value rather than having to explain all the caveats and details that need to be considered in OPS and FIP.
There are a good number of metrics on the market anymore, and deciding which to use is difficult. I'm partial to Tango's work, because it's all based on actual occurrences, actual run totals, and real numbers. The metrics based on his studies are the most encompassing and include the most detail, and I'm pleased to be able to present them here on Purple Row.
A lot of my information was taken from http://www.statcorner.com, where you can get the current tRA data for not only major league pitchers, but also for the minors down through A ball (Asheville as well as Modesto).
That's all for this week, fair RowBots. I hope to see us citing wOBA's and tRA's sooner than later when complaining about how hittable Aaron Cook has been this season.
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Let it be noted that I like tRA much better than FIP...
nice job explaining the concept.
Eschew Obfuscation!
FIP
I don’t think FIP was ever meant to be relied upon as much as it seems to be around here. It’s a quick and dirty stat, purposely scaled to fit to an ERA scale (so the formula should change when the league run environment does), and meant to be short hand for a group of stats people used to look at anyway (BB, HR, and K’s per 9).
I don't think that's quite what FIP was,
as RMN’s original article on it points out, the purpose was to evaluate pitchers without defense, not to be shorthand for another set of stats. I also think you read too much into when we cite it with the implication of your first sentence, just because it’s used doesn’t imply that the people who use it or are reading it on the site aren’t aware of its limitations.
Saber-types
are typically evaluating pitchers without defense when they look at things like BB, HR, K’s per 9, though of course I can’t speak for everyone when they do this.
Fantastic job...
Of introducing a very telling statistic to us guys who follow the basics of ERA, WHIP, K:BB ratio, etc.
tRA is a great concept, and looks to be a very useful statistic. For those of us who have watched the Rockies closely all season, that definitely looks to be the most accurate measurement.
"What's money? A man is a success if he gets up in the morning and goes to bed at night and in between does what he wants to do." -Bob Dylan
by Bryan Kilpatrick on May 20, 2009 11:16 AM MDT reply actions
If I understand correctly...
tRA isn’t really park neutral, is it? Is there an adjustment made for the percentage of FBs that become HRs?
How else is it normalized for park, etc.?
For instance, wOBA’s value is scaled to the league’s on base pct, but as it appears on fangraphs, it’s not adjusted for park.
It is park neutral.
We make a park adjustment for every input component that goes into calculating tRA and that includes how often fly balls leave the park.
That's awesome.
I didn’t know about the site until the thread. I’ll have to check it out, it looks great!
Right now, the individual players on the team pages displays un-adjusted wOBA.
The player pages show both wOBA (un-adjusted) and wOBA* (adjusted).
Looking at it, I have no idea why I decided to show the un-adjusted version on the team pages. I am going to change that now.
Ok, I see it now, didn't realize those player names were hyperlinked.
Very interesting site, thanks again!
No problem.
And I made the change; the team pages now show park adjusted wOBAs.
Heh
so Hammel is actually overachieving right now?
/barfs
That's what I was wondering
"There are three things in my life which I really love: God, my family, and baseball. The only problem - once baseball season starts, I change the order around a bit." ~Al Gallagher, 1971
JFK
Well, based on a 4.60 ERA, maybe
(I think I lost a post somewhere…sorry if this is a double-post)
I don’t think tRA breaks things down in terms of runs/unearned runs, or at least not to the stark degree as traditional scoring.
For instance, in yesterday’s ballgame 3 runs scored after what would have been the 3rd out. All 3 were thus scored as unearned. Undoubtedly the error hurt Hammel, but he also had a hand in some of those 3 runs.
I realize that
as I mentioned it during the game. Hammel needs to help get out of the inning, although his defense should help as well.
"There are three things in my life which I really love: God, my family, and baseball. The only problem - once baseball season starts, I change the order around a bit." ~Al Gallagher, 1971
JFK
Hammel has actually pitched very well despite horrid defense behind him...
which is why I’m surpised by his rating.
Eschew Obfuscation!
by Jeff Aberle on May 20, 2009 12:55 PM MDT up reply actions
Leave it to the engineer to be partial to empirical formulas ;-)
This is fantastic stuff. CR always helps me on hump day, but I honestly did not know much re: tRA…
…I’m surprised it didn’t treat Hammel better
"I have no special talents. I am only passionately curious." - Albert Einstein
by Andrew T. Fisher on May 20, 2009 11:59 AM MDT reply actions
thanks for that article
and thanks for making me laugh at
Neutral Planet Neutrals in Neutral Park with Neutral Defense behind him and the Neutral Neutralities batting against him
but i must ask, how does one
shake our hands miserably
if you're reading this, it means my undying support for your team will result in its failure.

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