Tuesday, February 14, 2012

What to Watch in 2012: Perkins' Slider

As we count down the days until pitchers and catchers report to Ft. Myers, I'm going to run a series of columns this week detailing some of the less high-profile story lines worth following in the 2012 season. We've heard plenty about the redemption quests of Joe Mauer, Justin Morneau, Denard Span and Francisco Liriano; in the coming days I'll be examining some other factors that could significantly impact the 2012 season. Today, I look at the pitch that turned around an embattled southpaw's career and could continue to entrench him as one of the game's best relievers.

After averaging just 4.7 strikeouts per nine innings over the first five seasons of his MLB career, Glen Perkins made the switch to full-time setup duties last year and the difference was night and day. In 61 2/3 innings at the back end of the Twins' bullpen, Perkins struck out 65 batters, good for a 9.5 K/9 rate that was superior to any seasonal mark he'd put up since splitting the 2006 campaign between Double-A and Triple-A as a 23-year-old.

Improved health and the freedom to let loose in shorter relief stints aided an increase in velocity across the board for Perkins, but while his fastball gained a few ticks, his most impressive pitch was a devastating slider, which showed remarkably more bite than we've ever seen from it in the past.

According to the PitchFX data available at Brooks Baseball, Perkins threw his slider a total of 440 times between 2008 and 2010, inducing only 47 swings-and-misses (10.7 percent). Last year, his much improved version garnered 60 whiffs on 276 deliveries, spiking his rate to 21.7 percent. That included a 27.6 percent swinging miss rate on two-strike counts, where the spinner was a dominant and very frequently used weapon.

Perkins' supremely effective slider enabled him to completely neutralize right-handed hitters, making him one of the few left-handed relievers in the league worthy of trust against batters from either side of the plate in late-inning situations. If his mastery with that offering continues, we could see him closing games before long.

7 comments:

Steve L. said...

I remember watching a game early in the season, late April I believe, and Perkins was in to pitch in like the 6th or 7th inning. He threw a pitch where all I saw was the Red flash around the MPH reading on FSN. Didn't believe it at first, but then I watched intently on the next pitches, 97, 96, 97. Then he threw a slider, and there was a much harder 2-plane break then he had ever shown before. Used to be more of a 10-4 break, but last year had some serious 11-5 action.

TT said...

What Perkins demonstrates is that the same pitcher can have much different stuff when moved to the bullpen. But the reliability of pitchfx data is pretty limited. Especially when used to identify what pitch was thrown.

In is numbers the differences that stand out are that, while he threw the same percentage of strikes, hitters swung more often, fouled off more balls and missed more often. His batting average on balls in play was .333 - 20 points worse than his career average.

It will be interesting to see whether he can repeat that performance. My guess is not. He had one great month in July last year, but he struggled after that. Its likely that those struggles will carry over, at least to some extent.

Steve L. said...

TT - I think his struggles at the end of the year can be attributed to his workload. The first three months of the season, he pitched about once every three days (or games). It became apparent he was their best reliever, thus in July and August he was pitching every other day, and it caught up to him.

TT said...

Steve -

Perkins may have worn out. But I don't see that great a difference in how he was used. And he missed a month on the DL over May and June. So if he wore out, that is still not a good sign.

I am not saying Perkins will be lousy next year. But I think his overall results are likely to be considerably worse. No one will be proposing him as a closer candidate any more.

Nick N. said...

But the reliability of pitchfx data is pretty limited. Especially when used to identify what pitch was thrown.

In certain cases, this is definitely true (e.g. cutter vs. four-seam FB). I tend to think it would be pretty accurate in identifying Perkins' slider, as he doesn't throw anything else that is particularly similar.

Perkins may have worn out. But I don't see that great a difference in how he was used. And he missed a month on the DL over May and June.

The difference in how he was used is relative to the rest of his career, not relative to the first two months of the season. Perkins warmed up and entered 65 games last year; his previous career high for appearances was 39.

While his workload, from an innings standpoint, was not extreme, the change in routine can be taxing on a pitcher whose arm has grown accustomed to doing it a different way. Kevin Slowey is a good example, albeit a far more drastic one.

Anonymous said...

But the reliability of pitchfx data is pretty limited.

Based upon what?

Especially when used to identify what pitch was thrown.

Pitch identification isn't a problem with Pitchf/x, it's a problem with whoever is doing the parsing of the data.

Steve L. said...

But I think his overall results are likely to be considerably worse.

I can see some regression due to hitters now knowing how he throws out of the bullpen, but the "stuff" he did throw last year was considerably nasty. Unless that regresses a bunch, I don't think he does much worse.