Colorado Rockies second baseman DJ LeMahieu will almost certainly regress, but how?

Among the many story lines obscured by the pyrotechnics of a certain Rockies rookie shortstop is the hot start of DJ LeMahieu. Despite going 0-for-4 on Sunday, DJ is hitting .341/.400/.585 on the young season. He's sat out two of the last four games in order to rest a sore groin but you can imagine why he might be eager to get the bat back into his hands.

It's hard to remember now but it wasn't until late 2013 that LeMahieu established himself as the everyday choice at the keystone sack (and even that was due mostly to his glove work). His defensive ability was beyond reproach, but offensively he failed to make significant contributions. Heading into 2015, LeMahieu was a .278/.317/.366 hitter with the Rockies and the book on him was fairly simple: a middle infielder who was proficient enough with the glove that any deficiencies were forgivable.

Needless to say his 2015 contributions at the plate came as a bit of a surprise. DJ was exceptional in the first half, riding a .311/.365/.397 line all the way to a start in the All-Star Game (he wasn't elected by the fans but c'mon, that's still pretty cool). He tailed off a bit in the second half but still finished with a .301/.358/.388 line on the season, good for a "close enough to league average" 92 OPS+.

So far this year he's off to another hot start, which begs the question: Which is the real DJ? It's unlikely that he'll be able to keep up this pace all season. Is he more likely to regress to 2011-2014 DJ, the .278/.317/.366 glove man who makes just enough contact to justify his spot in the lineup? Or to 2015 DJ, the .301/.358/.388 glove man who plays a key role in the offense?

Let's start with what DJ is most in control of: what he swings at. Here are his plate discipline numbers from last year, this year, and his career overall.

Fangraphs.com

Stats as of April 18, 2016

I should point out that those 2016 numbers looked even better before that three strikeout game on Sunday (he had a 12.2% K-rate going into the game), which just goes to show that we are still in the realm of small sample sizes. Even considering that, there are a few interesting things to note. First and most clearly of all is the home run per fly ball rate (HR/FB%), which sits at an eyepopping 28.6%. For comparison, Nolan Arenado's 42 HR season last year netted an 18.5% HR/FB% and in fact DJ's two long balls so far this year tied his career high in any month of his career. This, obviously, will not remain where it is, so we have a clear picture right from the onset where DJ is liable going to regress as the season wears on.

We can also see that DJ is transforming into a more patient hitter, willing to take a walk rather than swing at something outside of the zone (O-Swing%). This started last year and he is clearly continuing this approach in the early going of 2016. Once you establish you aren't willing to swing at pitches outside of the strike zone, pitchers have to throw you strikes or risk walking you. So far this year he is seeing more pitches in the zone (Zone%), which could be a sign that pitchers are approaching him differently as a result in this new skill, or it could be an early season fluke of the numbers. Either way, DJ is making more and better contact in the zone (Z-Swing%, Z-Contact %) so far this year, so it's something worth keeping an eye out for in the coming weeks.

Not only is DJ getting more balls in the zone, he is doing more with those balls so far. Take a look at the spray charts below. The first one shows DJ's first two years as the Rockies starting second baseman. Note the singles are spread fairly evenly across the field, the doubles and triples seem to be to the opposite field while the home runs are exclusively to the pull side.

Fangraphs.com

Now look at this chart, from last year. Those singles are heavily clustered in right field--€”the now famous LeMahieu Goes The Other Way Single--but the extra base hits are more evenly distributed across the ballpark, especially those up-the-middle doubles. The approach changed.

Fangraphs.com

Here's some numerical evidence, just in case you weren't sure.

Stats as of April 18, 2016

First compare DJ's career numbers to 2015. He hit the ball to the opposite field more (Opposite%), and hit more line drives (LD%) than he has for the rest of his career. This is how he took such a major step forward last year, by using an "inside-out swing" to hit the ball into right field.

Now bring 2016 into the mix and we can see a slightly different DJ LeMahieu. He is hitting the ball with even more authority (LD% is even higher, as is his hard hit %, while his ground ball rate is at an all-time low) and, perhaps more interestingly, he is hitting the ball up the middle and to the pull side more. This could be a result of him getting more pitches in the zone to hit, or it could be some early season flukyness. Regardless, if he is getting away from what made him successful last year it doesn't seem to be hurting him. That being said, while it's possible that DJ will continue smacking the tar out of the ball, these numbers are such outliers that I am skeptical that they can continue.

However, I do believe it is possible that the all-fields approach can continue because of the defensive shifts DJ will face. Infields usually play more or less straight up against him, but during the Opening Weekend series against the Padres we saw a radically new defensive alignment for DJ.

MLB.tv

From April 8, 2016

The Padres were trying to taking advantage of DJ's opposite field approach by overshifting their outfield to the point of almost having two right fielders (it didn't help the Padres much, as DJ still went 5-for-13 with three doubles in the series). Neither the Giants nor the Cubs tried this last week, but other teams might try something similar, especially if it proves effective. However, as long as DJ keeps spraying singles across the outfield it's likely nobody else will even try it.

It's pretty clear that DJ LeMahieu won't put up a slash line like 2015 Mike Trout for the rest of the season. The power will inevitably drop but we can also see that the strides he made in plate discipline from last year has carried into 2016 so far. As pitchers adjust to the hot start I'll expect him to get fewer pitches in the zone, or at least fewer pitches he can square up to massacre. The major trend I'll be keeping track of is where he's hitting the pitches. Was DJ "Shoots One into Right Field" LeMahieu a 2015 aberration or the real LeMahieu? Let's watch to find out.