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Major league implications of Tulsa's excellent starting rotation

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Advanced stats on minor league players are often hard to come by. But how can we use what's readily available to frame the conversation about the Tulsa Drillers' excellent starting pitching?


As the astute reader has certainly noticed by now, the starting rotation of the Tulsa Drillers (the Rockies’ Double-A affiliate for the slightly less astute) has had a decidedly remarkable start to the 2014 season. In fact, not one pitcher who has started a game for the Drillers has an ERA over 4.00. For that matter only one, Richard Castillo, even has an ERA over 3.00.

I’m not sure when was the last time this happened (if ever), and frankly it’s probably not worth looking up. What is worth examining from this phenomenon is how any and all of these young men project in terms of any future major league service time.

As it is often said, not all prospects are created equal. If you’re anything like me, you probably first noticed Tyler Anderson’s pleasantly surprising start while searching for the stats of Eddie Butler and Jon Gray. If you’re anything like me, you might have also found yourself uttering the question "Who the heck is Daniel Winkler?" upon stumbling onto Tulsa’s pitching stats. If you're anything like me, you probably didn't use the word 'heck' in the aforementioned scenario. Finally, if you’re anything like me, you probably wanted to know a little more about these four intriguing arms that the Rockies have stashed down on the farm.

Unfortunately, Pitch f/x and other advanced stats for minor league pitchers are not as accessible as most of us would like, so to a certain extent we all have to be reliant on the base stats and perhaps some scouting reports provided to fans through various websites out there.

But what if there was a better way? Is there a readily available stat out there that might help to project Major League success out of these pitchers? Some people use strikeouts per nine innings (K/9) as a good indicator of how good a pitcher’s stuff truly is, but as an organization, the Rockies don’t put much emphasis on a hurler’s ability to produce gaudy strikeout numbers, so that’s out. WHIP is a nice stat, and usually a reasonable indicator of future success, but to pontificate on the WHIP of four double-A starters as an indicator of their future Major League careers would be to waste the reader’s time, so what are we left with?

How about strikeout to walk ratio (K/BB)? Since control is largely considered to be the most valuable commodity a pitcher can have (not to mention the one that often takes longest to develop), K/BB ratio is generally seen as a better indicator of future success than K/9. And since Colorado’s front office has put a premium on pitcher’s who trend away from surrendering a free pass to first base, this might be a good way to explore the future prognosis of Tulsa’s young crop of pitchers.

It may not be the most ideal stat for projecting big league success, but it’s not the worst either, and it’s easy to calculate by hand.

First, we need some points of reference, so I took the liberty of pilfering Kevin Minor’s list of mid-season starting pitching call-ups since Ubaldo Jimenez (I included Jimenez too, for fun-zies), and calculated minor league K/BB for each pitcher.

It wasn’t as easy to standardize as I imagined it would be. For starters, players spend varying times in the minor leagues, and some of our sample didn’t even spend the majority of their minor league careers in the Rockies’ system. Without boring you with the tedium of methodology of each player, it is suffice to say that I took as large of a sample size as possible before each pitcher had seen significant Major League experience (that is, if they had a cup of coffee and then went back down, I didn’t hold the spot start or two against them), and whenever possible (i.e. large enough sample size) relegated the sample to Colorado’s minor league affiliates.





Ubaldo Jimenez



Jason Hirsh



Franklin Morales



Greg Reynolds



Jhoulys Chacin



Esmil Rogers



Greg Smith



Samuel Deduno



Juan Nicasio



Alex White



Drew Pomeranz



Tyler Chatwood



Chad Bettis


While obviously the jury is still out on the long term career paths of many of these pitchers, the correlation between a higher (i.e. better) ratio and big league success is reasonably strong. The correlation between the same and big league opportunities is much higher, as referenced particularly by Pomeranz and Nicasio, both two-pitch starters whose long term viability is shaky because of the drop off in secondary offerings.

As an aside, I'd still like to see Chad Bettis get the time he needs in the minors to develop. He has all the makings of a solid Major League contributor (as a starter or reliever) somewhere down the line.

Interestingly, the biggest outlier (as far as having a poor ratio yet still pretty successful) appears to be the pitcher that many would call Colorado’s best ever hurler in Ubaldo (I believe Chacin will eventually go down in history as better, but that’s a column for another day). It is worth noting however that even at his most effective, Jimenez struggled with walks, pitch counts, and all around control in general. So even as filthy as his stuff could be, his status as an exception in this case shouldn’t raise too many eyebrows. At any rate, he's the only pitcher with a K/BB of under 1.80 that is currently on a big league roster.

Now to move on to Tulsa’s electric foursome. Once again, for the sake of fairness, I took as much of a sample size as possible. All four have done all their professional pitching so far within the Rockies’ system, so their results should be the most standardized, at least compared to each other.



Tyler Anderson


Daniel Winkler


Jon Gray


Eddie Butler


That's a pretty sharp contrast to the list of mid-season call-ups. Among the previous crop, only Bettis had a better ratio than three of the four. Chacin's was higher than Anderson, but that is really it. If they are to be believed, the Rockies could have four of the best starters in club history pitching out in the middle of nowhere in Oklahoma right now.

Of course, the odds are laughably slim of that coming to fruition with all four of those starters. The numbers could also indicate that previously, the Rockies just didn't have much talent accumulated on their minor league pitching staffs. In fact, there are two very important ‘buyer beware’ warnings associated with these numbers.

First, as noted before, K/BB ratio says nothing about pitch selection. And once again, Juan Nicasio and Drew Pomeranz are the quintessential examples of this. That’s not to say that neither of them will ever amount to their lofty potential, but two-pitch hurlers typically struggle to make it as starters.

As far as it relates to Tulsa’s crew, Butler is regarded to have impressive secondary offerings, including a 90-mph changeup that ruins lives. Gray on the other hand, is seen as further behind in development because after his slider, his other secondary offerings remain a work in progress.

The other pitfall of using K/BB ratio to project success is of course, sample size. Try as I might, I can’t account for the fact that Jon Gray’s minor league career is only 79.2 innings old. By comparison, Winkler’s 408.1 innings seem like an eternity, but it inevitably makes his stats less subject to volatility.

At the end of the day, the real story shown here is not the imminent success of any or all of Tulsa’s starting rotation. Rather, it is a sign that this class of starting pitchers is ultimately what this Rockies front office will be graded on.

After all this time, the club’s front office, along with [relative] newcomer Mark Wiley and his title of Director of Pitching Operations, finally have a defined plan of how to pitch at Coors Field. More importantly, this new crop of pitchers is buying in. Fewer walks and pitching to contact to lower pitch counts and limit damage when the ball leaves the yard sounds sensible in theory, but ultimately the results will obviously determine whether it’s a successful plan.

If the minor league K/BB ratios can determine anything, it’s that the Rockies have gotten at least one of their minor league pitching staffs to buy in to this concept.

As far as I’m concerned, that means that after all this time, the clock finally starts when the first one is called up. Wish them luck.