From his rookie season through 2011, Robinson Cano batted .300/.343/.575 (116 wRC+) against lefties. Since then, he's hit a meager .234/.298/.352 (77 wRC+). It's certainly bizarre for a guy who previously showed no platoon advantage to suddenly lose the ability to produce against lefties. Is there any degree of bad luck? Has his approach changed? Have southpaws altered their pitch selection and Cano simply hasn't adjusted? These are some of the questions that have run through my mind. Considering how talented Cano is, the sudden drop off just doesn't make sense.
At first, I thought last season's issues may simply have been a blip on the radar, albeit something worth watching in 2013. In March, I wrote that based on BABIP and batted ball data, there was a pretty good chance of Cano snapping out of it. But now that he's accumulated 354 plate appearances against left-handers since last year, and there have been no signs of improvement, the concerns going forward have merit. For comparison's sake, his 2012-2013 77 wRC+ against southpaws is essentially the equivalent to Chris Stewart offensive production in 2013 (75 wRC+). That's not good.
Before getting into his batted profile, which is a head scratcher since it appears to have improved, let's delve into some alarming trends. Cano's power has dropped, with his ISO plummeting .057 points. Furthermore, he's striking out 5.5% more frequently than before. Per Russell Carleton's research over at Baseball Prospectus, K% and ISO stabilize after only 60 plate appearances and 160 at-bats respectively, so the decline in power and contact is no fluke.
As mentioned in the prior paragraph, the perplexing part of Cano's struggles is that it appears he's hitting the ball better than ever vs. lefties. A caveat with this is the accuracy of batted ball data, but even so we shouldn't figure Cano's line drive rates to be significantly skewed. Given the batted ball data from Fangraphs, I used a nifty xBABIP calculator embedded within this Fangraph's piece to "de-luck" Cano's performance against southpaws. Long story short, it uses a player's batted ball profile to figure out what his BABIP should truly be. So, if Cano's BABIP was actually .341 as the xBABIP calculator says, we could extrapolate the extra hits and assume he should have a .293 batting average and .352 on-base percentage against lefties. Now, this is probably far too optimistic, but an interesting perspective nonetheless. There's probably some degree of bad luck for Cano against lefties, but it's also very clear that his power and contact abilities have regressed.
Digging deeper, Texasleaguers.com can provide some details of southpaws' approach to Cano. Unfortunately, the PITCHf/x data on the site only goes back to 2008, so the comparison will be between 2008-2011 and 2012-present. The way pitchers have approached Cano hasn't changed, attacking him down and away primarily:
As far as pitch selection, fastball (Four-seam, two-seam, cutters combined) usage is down just 1.6%. Slider usage essentially makes up for that difference, up 1.7%. Other offerings barely changed between the two time periods. It is worth noting that the PITCHf/x system does make pitch classification mistakes, so there's a decent chance that Cano is seeing closer to the same proportion of pitch types as before. The noticeable change is his whiff percentage, in particular against cut fastballs, against which he's feeling the breeze 4.8% more often than he did between 2008 and 2011. He's whiffing 2% more often against four-seamers, and a hair under 1% more frequently against sliders. That explains his increased strikeout rate against lefties.
What about Cano's approach against same-siders?
It's not as easy to see, but it appears that the greatest concentration of outs Cano has made since his struggles against lefties have come about is to the right side of the field; groundouts in particular. 2011 and prior, Cano effectively hit the ball to all fields against lefties. Now, although there appears to be a fair balance of hits to right, left, and center, the outs are heavily clustered on the right side of the infield. What does this mean? Well, knowing that the approach of the pitchers haven't changed (away, away, away), perhaps Cano is trying to pull the ball too often. Simply put, it's possible that Cano is rolling over pitches to the right side that he used to lace into left field. It seems to be a reasonable conclusion given the opponent's approach. Overall, he's become more of a power hitter the past couple of seasons, which could explain why he may have become pull happy.
While it still seems that Cano has run into some bad luck, and that a change in hitting approach could be beneficial, the two arguments are probably too simplistic in nature. What we've seen from Cano against lefties since 2012 may simply be who he is going forward. In fairness, though, I don't see why Cano can't at least be league average against lefties. It certainly would be a huge boost to the offensively challenged Yankees, who can't really afford their best hitter turning into Chris Stewart when a lefty comes around.