Archive for expected BABIP

In rounding out my series on the most important factors influencing components of BABIP, I will be looking into what most affects a hitter’s batting average on ground balls. So far, the results of these analyses have been consistent. Launch angle has been the main driver of BABIP for pitchers, and it has been for hitters as well, at least when they are launching flyballs. The story is a different one, though, when hitters put the ball on the ground. Ground ball launch angle was not a significant factor in determining a hitter’s ground ball batting average, and neither was ground ball exit velocity.

Whether or not a hitter pulls grounders has much to say about whether that player will hit for average on grounders. There is a negative relationship between these variables that is significant at p < .0001 and with a Pearson’s r of .27. Even more important is how fast the hitter is. The Pearson’s r for the positive correlation between average sprint speed and ground ball batting average was .45.
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Contributing to RotoGraphs’ Bullpen Reports last year brought me much joy: opening infinite Brooks Baseball player cards for sabermetric outcomes and watching glorious GIFs. Oh, Marcus Stroman’s Two-Seamer:

GIF: Marcus Stroman’s Two-Seam Fastball from last week’s outing. It may be our favorite of the year – http://t.co/vyJM8ltUir

— Pitcher List (@ThePitcherList) August 31, 2014

Mmm.

My last Bullpen Report from October looked at possible closers through outcomes and presented BABIP differentials (actual BABIP versus expected BABIP using Inside Edge data).

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Year in and year out, Ichiro is a model of consistency. He has had over 200 hits and a batting average over .300 every single season he’s been in the majors. He’s also scored at least 100 runs every year, and stolen at least 30 bases. That being said, what can we expect from 2009?

The short answer, of course, is more of the same. When a player is this consistent for this long, the best predictor of his performance is his past performance. With that in mind, Ichiro is also getting older – he’ll be 35 next year, and even though he is a unique player, he’s not totally immune to the effects of aging. In fact, this is already beginning to show up in his batting average.

In 2008, Ichiro hit “only” .310 – the second lowest batting average of his career (in the North American Major Leagues, that is). However, he managed this batting average despite a higher-than-expected BABIP – his actual BABIP was .330, but his expected BABIP (according to a new model I introduced) was .307.

Before you tell me that Ichiro is unique, hear me out: yes, I agree that Ichiro is unique, but this new model attempted to incorporate many of the elements that make Ichiro unique – such things as hitting to all fields and speed, two elements of which Ichiro makes particular use.

I wouldn’t disagree that, even though the model has attempted to incorporate the unique aspects of Ichiro’s game, it hasn’t fully succeeded. Here are Ichiro’s expected and actual BABIPs since 2005:

Note the average: since 2005, the model has underrated Ichiro’s BABIP by approximately 23 points. Now, I think this is somewhat unfair, as the average is severely skewed by Ichiro’s incredibly-high BABIP in 2006, which was well out of line with even his own already-high numbers. But if we assume that the ~23 point difference is correct, well…that means Ichiro’s BABIP in 2008 was completely luck free.

What’s perhaps more interesting to note is the downward trend of Ichiro’s expected BABIP – it has declined each year since 2005. This goes along with conventional aging patterns – Ichiro was 31 in 2005, and as he exited his prime, his expected BABIP slowly dropped.

This suggests to me that Ichiro’s batting average is a lot more likely to go down than it is to rise. Of course, it’s certainly possible that he has another flukey BABIP year that allows his BA to rise once again, but this is increasingly unlikely as he gets older. Even though Ichiro’s .310 batting average was the second lowest of his career in 2008, it doesn’t appear that this was a fluke, but rather was indicative of him slowly getting older. That doesn’t mean Ichiro won’t have significant value in fantasy leagues next year – after all, he’s still shown that he can steal 40+ bases and hit over .300 – but don’t draft him expecting a resurgence to the AL batting title.

Jimmy Rollins probably left many fantasy owners disappointed last year. He hit .277/.349/.437 with 11 homers and 47 steals in 137 games. Obviously, those are good numbers, but they are may be a little below what optimistic owners were expecting. What can we expect from Rollins in 2009?

Let’s start with batting average. Rollins hit .277 last year, after hitting .296, .277, .290 and .289 over the last four seasons, respectively. Rollins’s strikeout rate was actually the lowest of his career last season, as he struck out in only 9.9% of his at bats. Over the last five years, his K rate has hovered right around 10-12%. However, last season Rollins’s BABIP was .285, but his expected BABIP (according to a new model I introduced) was .323. If you add in those “missing” hits, Rollins’s batting average becomes .311.

Additionally, Rollins improved his walk rate in 2008 – he walked a career-high 9.4% of the time, the first time in his career that he was even over 8%. This led to the highest OBP of his career, despite the (relatively) low batting average. As a result, Rollins had more opportunities to steal bases. Furthermore, he stole bases at an incredibly efficient clip, getting caught just three times in 50 attempts; this continues a trend that began in 2005 – since (and including) that year, Rollins has been successful on 165 of his 184 stolen base attempts, an impressive 90% conversion rate.

Perhaps the most disappointing thing about Rollins’s 2008 was his power – or lack thereof. He totaled only 11 long balls, after hitting 55 over the previous two seasons combined. Part of the problem was that Rollins played in only 137 games in 2008, after having played in every single game in 2007 and 158 games in 2006. More of the problem appears to be the fact that Rollins stopped hitting fly balls – only 30.6% of his balls in play were fly balls in 2008. In 2007, Rollins hit fly balls 44.2% of the time, but that appears to be an outlier in his career: in the three seasons before 2007, his fly ball percentages were 36.9%, 32.1% and 35.8%.

His fly balls became homers at a lower rate in 2008 (7.7% of his fly balls left the park) than in the past two years (11.1% and 10.7%, respectively), but his career HR/FB is 8.8%. The biggest problem was Rollins reverting to his ground ball tendencies – an issue that could have to do with faulty mechanics and/or the sprained ankle that sent him to the DL in April (although I highly doubt a sprained ankle would sap a player of his power). However, it could simply be that Rollins’s 2007 season was a fluke in terms of fly balls – he hasn’t hit nearly as many fly balls in any other season.

If we assume that Rollins’s fly ball totals from 2007 were out of whack, so too must we assume that the 30 homers he hit that season are likely going to be a career high. It’s certainly possible that Rollins will regain some homers from his dismal 2008 year (dismal in terms of power production, that is), as his fly ball rate will probably rise somewhat, and he could see a slightly higher proportion of his fly balls leave the park. Still, an increase in these two areas would probably yield somewhere around 15-20 homers, maybe 25 (assuming Rollins stays healthy all season). As Rollins will be 30 years old next season, it’s quite likely that he won’t match his age with his homer total ever again.

However, even accounting for Rollins’s relative lack of homers, it appears that he improved his game in other facets this season – improvements that he may carry with him into next year. Rollins is still an incredibly efficient base stealer who also runs often, and this should continue next year. Furthermore, if Rollins can take his improved strikeout- and walk-rates with him into next season, he could see a rise in his batting average (remember, his batting average should have been .311 this year) and OBP, leading to more opportunities to steal bases and more runs scored atop a powerful Phillies lineup.

You shouldn’t draft Jimmy Rollins expecting 30 homers, but you can reasonably expect 15-20 bombs, and perhaps even a batting average of around .300 and upwards of 50-60 steals. That’s still a heck of a player, especially for a shortstop.