Altherr’s Hot Start Hides Underlying Weaknesses (and Improvements)

It is not a controversial statement to say that Aaron Altherr is headed for some regression. His BABIP (.392), HR/FB rate (35.6%),and ISO (.381) are way outside of expected norms. The good news is that he is batting .333/.434/.714, so any regression would take him from an MVP pace to just a really good baseball player. When a player goes on a hot streak, it has a tendency to cover up underlying numbers.

For Altherr, his big underlying discrepancy is his left/right split. Here are his triple slash lines vs righties and lefties:

Vs RHPs: .333/.433/.684

Vs LHPs: .333/.438/.778

It isn’t surprising that he is hitting for more power vs lefties. But, this only tells a surface story, so let’s unpack this a bit more with some different stats.

Vs RHPs: 67 PA 11.9% BB% 31.3% K% .452 BABIP

Vs LHPs: 32 PA 15.6% BB% 12.5% K% .300 BABIP

Now we start to see three different trends. The first is that Altherr is just obliterating left handed pitching. The second is that Altherr has some concerning trends vs right handed pitchers. His BABIP will regress, but we aren’t sure whether his strikeout rate will come down. Given that we expect declining performance vs right handed pitchers, the final trend is concerning, and that is the playing time split between RH and LH plate appearances (keeping in mind that Altherr started the year in a platoon role, which helps even these numbers out). We saw this last year with Darin Ruf and at times with Tommy Joseph, that being the right handed side of a platoon just doesn’t present many opportunities.

On the strikeouts, we are starting to see where pitchers are attacking Altherr. From Brooks Baseball, here are the pitches that Altherr is swinging at:

Altherr Swing Percentage – BrooksBaseball

Let’s now compare that to where he is missing when he swings.

Altherr whiffs/swing – BrooksBaseball

We see two hot spots, one is down and away and the other is up and in. If we go back to the first chart, we can see that he just isn’t swinging at the pitch away, and if we were to pull up a pitch percentage graph, we would see that bottom right zone is where pitchers are throwing the ball at the highest rate to Altherr. He does have two weaknesses that pitchers have been able to exploit. The first one is up and out of the zone (but not in). He will swing at the pitch at a high rate and will almost always miss it. You can also get him to chase down and out of the zone. The only problem is this heat map.

Altherr SLG – BrooksBaseball

Both those high miss zones are right near where there has generated a lot of his power. So there are weaknesses to attack, but they are high risk, and pitchers without great control could find themselves leaving a pitch in a great place to hit.

We are now into the second month of the season, which means for Altherr there is some small sample size trending data.

Handedness Month PA AVG OBP SLG BB% K% BABIP
vs LHPs
April 16 .200 .250 .467 6.3% 18.8% .182
May 16 .500 .625 1.167 25.0% 6.3% .444
vs RHPs
April 32 .345 .406 .552 6.3% 34.4% .529
May 35 .321 .457 .821 17.1% 28.6% .357
vs Both
April 48 .295 .354 .523 6.3% 29.2% .393
May 51 .375 .510 .925 19.6% 21.6% .391

Now this is all extremely small sample size, and we have to account for the fact that pitchers might be pitching around Altherr somewhat, but what we see is distinct improvement. Against lefties, Altherr went from unlucky and unproductive to a monster, and against righties he has offset a 150 point drop in BABIP by hitting more home runs and cutting his strikeout rate. Aaron Altherr is on an insane hot streak, and we all know his stats are going to regress. However, we can see that under the gaudy stats he has some weaknesses at the plate. We can also see that he has already started to make the adjustments to make those weaknesses less damaging to his overall success. It will be interesting to see if pitchers start to adapt to his adjustments and start trying to elevate to him and not try to get him to chase away. For now it all seems to have clicked, and hopefully we continue to see him crush everything forever.

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  1. WE

    May 15, 2017 04:44 PM

    Pretty much everyone has trouble with up & in and down & away. That’s baseball.

  2. Pete

    May 15, 2017 10:49 PM

    Thank you for this, Matt. You read my mind. As I was opening Crashburn I was hoping for an article analyzing Altherr’s start.

  3. Mike Fassano

    May 16, 2017 03:57 AM

    Aaron Altherr is the feel good story in Philly this summer. Can I enjoy it while it lasts, or should I bunker down for when he crashes back to Earth?

    • Romus

      May 16, 2017 08:50 AM

      Cesar is also a feel good story so far this season.
      And his base running has improved…he has only been picked off once in the first six weeks.

  4. ASK

    May 16, 2017 07:28 AM

    Great stuff, Matt. 2 question about Altherr’s numbers against RHP’s.

    1. Is there a site which shows exit velocity broken down per a hitter’s different splits? From the eye test of the games I have seen (albeit a very unreliable test), it seems as though Altherr has either K’d or hit the ball very hard against RHP’s.

    2. If exit velocity vs. RHP’s confirms what my eye test shows and in the small sample size of this season it has in fact been almost exclusively feast (hard hit balls) or famine (K’s), should we expect to see both his BABIP and K% drop in a highly correlated way as some of those K’s turn into weaker contact?

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