Corey Hart finished for season; did plate discipline impact his power?

Corey Hart’s season is over after x-rays showed possible compression fractures in his right hand, stemming from his fourth and fifth fingers. Bone scans will later confirm the story, but there’s no way Hart returns to the ballfield in 2009.


As a result, the right-fielder finishes his season with a .260/.335/.418 line, disappointing in the power field given he had knocked out 20 and 24 home runs, respectively, the two previous seasons. This year, in roughly 100-200 less plate appearances than 2007-8, he finished with just 12 in 472 PAs.

While the power sapping could partly be attributed to the emergency appendectomy that knocked him out for a stretch of time earlier this year, manager Ken Macha has other ideas.

“We were trying to get him more disciplined at the plate and not swing at sliders out of the zone, and we accomplished that,” Macha told the Milwaukee Journal-Sentinel. “But we took away a little bit of the aggressiveness, maybe sapped him of his power.”


There’s no question he boosted his plate discipline — simple numbers bear that out. Here are his walk percentages since 2006, when he began amassing significant at-bats.

6.7, 6.7 (there’s something to be said for consistency), 4.2, 9.3.

Taking a glance at ratios that bely power numbers, let’s check line drive percentages out across the same time period: 16.7, 17.1, 19.2, 17.2.

One more; home runs per fly ball percentage: 12.2, 13, 9.9, 8.8.

While there may appear to be a correlation between his low walk total and line drive percentage, his best power season came in 2007 when he posted near identical line drive numbers while juicing balls out of the park at a better clip. He’s hit additional ground balls on the year percentage-wise than fly balls, but that’s generally a moot point when you’re talking a difference between a ground ball and a fly ball — ground balls aren’t going to go out of the park and likely shouldn’t be considered.

The additional ground balls may be a factor in his weakness from appendectomy or a mechanical flaw, but to say that improving his plate discipline has “sapped” his power is shaky logic. I don’t pretend to have answers, but I do know that I don’t agree with Macha.

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Dave Studeman
14 years ago

We talked about Hart a lot in the Batted Ball Reports this year, focusing on him in mid June.  At that time, he had a 13% home run rate on outfield flies. His walk/HBP rate was 9% then, 10% now. His swings out of zone are down this year, according to Fangraphs.

However, the real key is his line drive power.  Historically, he had produced .5 runs per line drive, almost a tenth of a run more than major league average.  This year, he’s down to .33 runs—over .05 runs less than average.  That’s down a bit from where he was in mid-June (.38).

The proof has been in his line drives, not his fly balls.

By the way, to me, Hart is one of the more interesting batters in the majors because he’s a unique combo of some line drive stroke, some power, relative lack of plate discipline and (surprise) very good ground ball hitting.  He’s consistently had an above-average batting average on grounders.  Over the past four years, he’s produced more runs above average on ground balls than either line drives or flies.

A good comp is Matt Kemp, though Kemp is better in line drives and power. Hunter Pence and Ty Wigginton have similar profiles historically.  But that’s about it.

14 years ago

I think plate discipline might well have been the reason. The reality is that many hitters just aren’t cut out for being disciplined at the plate and it can have an impact on their performance.

I can recall one year when the Cubs convinced Shawon Dunston to be more selective at the plate. In the first month of the season, he was walking like crazy but he was only hitting .180. Don Zimmer started playing Domingo Ramos in his place and Dunston finally started swinging away and immediately went on a tear.