Explaining Moustakas' slump

With all of the talk about moving Alex Gordon out of the leadoff spot (a move I disagree with), no one has mentioned what prompted the move in the first place. Mike Moustakas is the latest young Royal to be moved out of the three hole because of a lack of production, and the more you look at his numbers, the further Moose looks from returning to the middle of the lineup any time soon.

Moustakas's season numbers have been way more palatable compared with Eric Hosmer because of Moustakas' good start in April when he hit .315/.375/.534. But reality is that Moustakas has maybe been the Royals worst hitter outside of Jeff Francoeur since the beginning of June.

From June 1 to Aug. 16

Hosmer: 255 PA, .257/.333/.365, 25 bb, 44 k, WPA +1.3

Moustakas: 258 PA, .236/.282/.413, 15 bb, 54 k, WPA -1.9

Francoeur: 248 PA, .212/.246/.322, 8 bb, 52 k, WPA -3.9

*WPA (Win Probability Added) measures the amount of wins or losses contributed by a player given an average team.

Frankly, Moose hasn't been much better at the plate than Hosmer all season. According to Bill James, Hosmer's win shares for hitting is only .1 below Moustakas' 5.8. Take away April and Moustakas is hitting .237/.289/.423 while Hosmer is batting .245/.312/.350 in that span.

Many like to take refuge in Moose's home run total, 18, and his improved defense* this season as a way of looking past the totality of his offensive performance. But it should be noted that 14 of his home runs are solo shots, and only Francoeur is batting worse than Moose's .239/.286/.367 with men on base among every day players this season for the Royals.

*There is no question Moustakas defense has been an asset this season, his nine runs saved according to the Fielding Bible has him ranked third amongst all third basemen. It is interesting to note, though, almost all of his improvement has come from his ability to make plays to his right -- down the third base line -- and that his performance against balls hit right at him or to his left has been at or below average. Using the plus/minus system, Moose has a +19 to balls hit to his right, 0 on balls hit straight on and a -4 on balls hit to his left.

So when exactly should fans begin to freak out about Moustakas the same way they've been freaking out about Hosmer?

The good news for Moustakas is that the reasons for his problems are easier to identify than Hosmer's and can (hopefully) be easily corrected.

Fangraphs and Baseball Prospectus use Pitch F/X data to record what kind of pitches a batter is seeing, the location a player is swinging at pitches, how often he makes contact and if the pitch was in or out of the strike zone. Last season, Moustakas swung at about 33.2 percent of pitches thrown outside of the strike zone and made contact with 72.3 percent of those pitches. He was making a lot of contact with those pitches because he was seeing a lot of fastballs. Over 42 percent of the pitches he saw last season were fastballs.

And Moose loves fastballs. Seventeen of his homers this season have come on fastballs. He is batting .285 on fastballs that are for strikes and is batting .315 on fastballs left in the middle or lower third of the strike zone. A fastball for a strike to Moose is almost always going to mean good things for the Royals.

The rest of the league knows this and Moustakas is seeing way fewer fastballs (32.3 percent) and a lot more sliders (14.2 percent up from 11.1 percent) and curveballs (13 percent up from 9.9 percent). Moustakas is chasing more pitches outside of the strike zone (36.3 percent) and is making less contact with those pitches (64.4 percent). And it isn't that Moose cannot hit a breaking ball. He is hitting .279 with a home run against sliders and curves left in the zone in comparison to .175 against sliders and curves outside of the strike zone.

Because Moustakas is chasing so many pitches outside of the zone pitchers have essentially stopped throwing strikes to Moose, throwing just 46.1 percent of all their pitches inside the strike zone. This problem is more highlighted when he faces left handed starting pitching, against whom Moose is hitting a lousy .225/.256/.383 with 26 strikeouts (and five walks) in 125 plate appearances.

If Moustakas can figure out a way to better recognize breaking balls as balls or strikes, he should be able to repeat months like April more frequently by forcing pitchers to throw him more strikes and more fastballs. If he does figure that out then Moose can be one of the most valuable players in baseball.

| Ben Nielsen, bnielsen@kcstar.com