Q&A: Glen Perkins, Stud Reliever & Stat Geek

The numbers show that Glen Perkins has been an effective pitcher since moving from the starting rotation and into the bullpen. The Minnesota Twins southpaw knows those numbers as well as anyone, and not just his won-lost record, his ERA and his WHIP. He’s also aware of his BABiP, his FIP and his WAR, as well as most anything that can found in his PITCHf/x data.

Prior to a recent game at Target Field, the 29-year-old talked about his move to the bullpen, his repertoire and his interest in stats.

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Perkins on his success pitching out of the bullpen: “A big reason has been more confidence, and the mental side of it came with the physical side. Going to the bullpen allowed me to get healthy. As a starter, I had just worn down.

“A positive was that pitching with inferior stuff taught me to be able to command the ball. It also taught me to set up hitters and recognize what they’re trying to do. There are nuances in the batter’s box that I can pick up on now that I never used to be able to. I needed to get any kind of advantage when I had bad stuff.

“My stuff got better when I went to the bullpen. I got healthy and started throwing harder. I actually kind of went back to my first year in the big leagues. In 2007, I was a reliever and was throwing a lot harder than I did in 2008 and 2009. Along with the increase in fastball velocity, I’ve become a lot more comfortable with my slider. I have a two-pitch mix that I’ve learned to work with. When you throw 95-96 [mph], hitters can’t stay on a fastball that quick, and then a slider.

“I got pounded pretty good in 2009, my last year as a starter in the big leagues. I wouldn’t say that I had confidence issues, but in the back of my mind I kind of wondered if I could get big-league hitters out. Last year, as the season went on, I got more and more confident and I’ve taken that into this year. I think that’s probably why my strikeout totals are higher than they were last year. I realize when to attack. I realize when a guy is vulnerable to a strikeout and can take advantage of that.”

On his slider: “My fastball and slider are both better than they were in 2009 and 2010. They’ve also gotten better from last year. My fastball velocity is up a little bit and I think I have a better thought process on my slider. When I miss with sliders, they don’t hang like a typical slider and just kind of spin up there. I’ll spike them into the ground. I can probably count on one hand how many I’ve hung this year. [Alfonso] Soriano hit a home run on one of them.

“I’m maintaining arm speed on my slider, and I have a better feel for it. I had never thrown a slider until the middle of the 2008 season. I had never thrown one in my life. It started getting really comfortable in 2010, when I was in Triple-A. I turned the corner when my slider really took off. If there’s a time where I really need to get a strikeout, I’m probably going to throw my slider.

“When I throw my slider, it looks to me like it breaks a lot. When I look at PITCHf/x and see the numbers on my horizontal and vertical movement… I have an idea of how that works, but last year it was classifying a lot of my sliders as changeups. I’d look at them on video and it certainly didn’t look like they were breaking [the wrong] way. They were still breaking to the back foot of a right-handed batter. I haven’t seen that problem since midway last year, though. I actually told our video coordinator about it, so maybe he put a call in to ask them to check it out. I’m not sure.”

On velocity, location and his fastball: “I go to Brooksbaseball.net to look at the locations. I like to see how close I can get to the corners. You can only learn so much from what you see on video — where the pitches actually cross the plate. I’ll go there to see if I’m getting my pitches on any of the four edges of the strike zone. I don’t rely on movement with my fastball. I rely more on velocity and location.

“I’ve been able to command my four-seamer this year, so that’s the one I’ve been going with. Last year I was at about 50% with my ground balls, and in a way I’d like to be there, because ground balls don’t get hit for home runs. I guess I’ve traded ground balls for strikeouts and that’s a good trade off as long as I’m not giving up home runs.

“As a pitcher, it’s hard not to be aware of your velocity. It’s on the top of the page and there are radar readings all over the stadium. If you turn around, you’ll see them. If you see your outing on TV, there’s a radar reading there. If a guy says he doesn’t know, he’s usually lying.

“I’m not really throwing a changeup anymore. I’ve probably only thrown three all year. I threw two to Michael Young. He had about a nine-pitch at bat and I couldn’t bury a slider or get a fastball by him, so I threw him a changeup and he flew out. Usually, when I’m feeling good on the mound, the at bat is going to be over in three or four pitches.”

On FIP, BABiP and WAR: “I like a lot of stats and go onto FanGraphs pretty much every day. I like FIP and xFIP, which give you an idea of whether you’re doing the right things. Not that it’s something you can control, but you know that if it’s down — and you keep doing what you’re doing — the balls are going to find fielders. If your FIP is one thing and your ERA is higher, they’re probably going to meet in the middle. My ERA this year started out high and came down to closer to what my fielding-independent is.

“I didn’t get frustrated with my bad ERA. I had given up a couple of home runs and felt that maybe some balls were finding holes. You can’t start thinking, ‘Now I have to strike every guy out.’ Understanding that things should even out gives me confidence in what I’ve done. [FIP] shows that I should be here, and not here.

“I do get a little frustrated with my BABiP. I’ve always had a high one, and it’s high again this year. I also don’t have my ground-ball rate down, but I’ve focused more on fastballs up in the zone and sliders down in the zone. Last year, my two-seam and four-seam were a more even distribution. It’s more four-seamers this year, so I’m getting more fly outs.

“I like WAR, but I don’t like it for relievers. I think it’s a good stat for starting pitchers and everyday players, because it’s a bulk stat. I don’t think you can quantify relievers the same way you can quantify a starter. You need to break off them into a separate group to see where they stand. My numbers as a reliever are going to be different than they were as a starter.”

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Note: Perkins has agreed to be the featured guest on FanGraphs Audio this Thursday. Readers are invited to include questions for him in the comments section of this interview. Many of those questions will be included in the conversation. The deadline for questions is 2 p.m. [EST] on Wednesday.