The Yankees have signed DJ LeMahieu to a two-year deal to reinforce their infield; though he's been primarily a second baseman, he'll likely also see time at first and third.

He's a good defender joining what's a below-average defensive infield, so that alone is an improvement, but that's also not the question that's worth asking now. As with every successful Rockies hitter who departs Coors Field, we have to dig into the home/road splits and wonder: Was this guy only good in Colorado? Does leaving mean he'll be a shell of what he was?

Yes. And no. It's complicated. In LeMahieu's case, it's even more complicated, thanks to some underlying interesting numbers that maybe, just maybe, show that there's more in the tank.

Coors Field definitely helped LeMahieu, a lot

This is unavoidable. At home, LeMahieu was a star. On the road, he wasn't nearly the same. While he's not a traditional power hitter -- his 15 home runs in 2018 were a career high -- there's a misconception that the primary effect of Coors Field is to add power, and that's just not true. The biggest impact is that the enormous outfield is too large for outfielders to cover, and that creates more non-home run hits.

This was true for LeMahieu in 2018.

• Home: .317/.360/.433, .793 OPS, .351 BABIP

• Away: .229/.277/.422, .698 OPS, .232 BABIP

And it's been true in his career, which includes nearly 3,800 plate appearances over seven years with the Rockies.

• Home: .330/.387/.448, .835 OPS, .376 BABIP

• Away: .264/.311/.362, .673 OPS, .307 BABIP

Those are enormous differences. You can't simply look at his career stats and assume that's what the Yankees are going to get, because LeMahieu's going to be losing the enormous benefits of playing at altitude.

On the other hand, you can't just look at that poor .673 road OPS -- and it is poor, as it's basically what light hitters like Amed Rosario or Manuel Margot had in 2018 -- and assume that the Yankees signed up one of the weakest hitters in baseball. This is where it gets complicated.

Coors giveth, and taketh away

There's no doubt that calling Coors Field home helps a hitter. This has been endlessly proved, and a quick look at splits for Nolan Arenado , Trevor Story , Charlie Blackmon, or LeMahieu proves that pretty well.

But there's also evidence that calling Coors Field home hurts you on the road, too.

We looked into this back in 2015, and this is the relevant section to surface here in 2019:

For example, over the past 10 seasons, the Rockies scored 4,596 runs at home, unsurprisingly the most in baseball. But over the same period on the road, they scored 3,089 runs, the fewest in baseball, 151 runs behind 29th-place Houston. In order for both of those things to be true, either Coors Field would have to elevate baseball's worst offense to play like its best, or a middle-of-the-pack team would have had to receive positive effects at home and negative effects on the road -- which seems far more realistic. You can call that "the Coors Field effect."

Name your theory as to why that is, including:

• Visiting pitchers don't trust breaking pitches at altitude, so they throw more fastballs, which makes Rockies hitters more aggressive at home and too aggressive on the road,

or

• Rockies hitters don't see good breakers at home and aren't prepared to face them on the road.

Either way, this manifests itself in more than simply hits and homers. It affects contact. In 2017-18, Rockies hitters were tied for the 11th-lowest strikeout rate at home, yet had the fourth-highest strikeout rate on the road. It's the same thing for LeMahieu, who had a 12 percent strikeout rate at home, and a 16 percent mark on the road.

Now, you might just say that the road numbers are the "real" numbers, and only the home numbers have changed, except that we've seen road improvement from departing Rockies in the past, as we wrote in 2015 with Matthew Holliday , William Fowler , Seth Smith, Chris Iannetta and Clint Barmes.

In fact, let's update the numbers for Iannetta, because he's a perfect test case; after leaving the Rockies for six seasons, he returned to Denver in 2018. After being essentially even home/road in 2008, he was markedly better at home in 2009, 2010, and 2011. Then he departed, and he was better on the road every single year.

When he came back to Colorado in 2018, look what happened.



LeMahieu's home stats are probably going to drop off, because they always do, but there's at least some evidence that shows his road stats might improve, too. (Not likely enough to match the home-field decline, to be sure. But not nothing.)

Of course, that all assumes that LeMahieu himself will be the same player that he's always been, just in a new park. Is that true?

Some underlying reasons for hope

The thing about LeMahieu is that, despite never being a power hitter, he's been able to hit the ball hard. Over the last three seasons, 439 different batters have made contact with at least 250 batted balls, and LeMahieu's 43.8 percent hard-hit rate is tied for 33rd, ahead of more notable sluggers like Kyle Schwarber , Chris Davis and Freddie Freeman.

That hasn't necessarily led to big home run totals, because he has hit too many grounders. In the same span, LeMahieu's 53.6 percent ground-ball rate is 41st, or far too high.

Of course, there's evidence that's changing, as he finally got down near the 50 percent threshold for the first time in 2018.

Ground balls are bad, and DJ LeMahieu seems like he's trying to stop doing it. pic.twitter.com/x9sU76OniQ — Mike Petriello (@mike_petriello) January 11, 2019

So that's a good start, in that you've heard the "guy with good hard-hit rate stops hitting grounders and finds success" story before, but there's more. For years, LeMahieu was an extreme opposite-field hitter, at least in the air. On non-grounders, from 2015-17, no righty hitter -- and only Joe Mauer among lefties -- put more air balls to the opposite side, as LeMahieu did nearly 56 percent of the time.

(You may remember that because of this, in 2017, the D-Backs trotted out what was a very unusual outfield alignment against him.)

A.J. Pollock's catch on DJ LeMahieu's lineout in 5th inning last night. Almost certainly wouldn't have made w/o shift. pic.twitter.com/BoxpAeUUqC — Daniel Kramer (@DKramer_) September 2, 2017

But in 2018, that began to change too. That 56 percent opposite-field air-ball rate dropped to only 41 percent. LeMahieu began to hit the ball in the air more, and he began to pull it more, and he retained his ability to hit it hard. If that sounds very much like the man who essentially replaced him in Colorado, Daniel Murphy , it ought to. It's a strong way to tap into what may be untapped power.

There's an argument, of course, that the old opposite-field hitting ways ought to return, considering the fact that his new home park in Yankee Stadium is famous for its short right-field porch.

But then again, that's really the point, that there are so many unknowns. We don't know if the raw skills LeMahieu has will play up with a new coaching staff and in a park that's a different kind of hitter-friendly. We don't know if LeMahieu can really play first and third, positions he hasn't touched since 2014. We can't really make a case that LeMahieu and Troy Tulowitzki was a better direction than getting Manny Machado.

What we do know is that you can't just look at lousy road stats away from Denver and assume that's the player that the Yankees just bought into. It doesn't quite work that way. It's rarely that simple.