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Mound Musings: ERA vs. xFIP

David Regan

David Regan is a six-time Fantasy Sports Writers Association award winner, including the 2015 Baseball Article of the Year.

Today let's analyze pitcher performance in terms of his actual performance (ERA) versus how he should be expected to perform as measured by a commonly-used sabermetric statistic, xFIP. The "FIP" portion refers to Fielding Independent Pitching, or things pitcher controls. Studies have shown that pitchers exercise little control over whether a batted ball falls for a hit, so let's look at what he can control - strikeouts, walks and home runs. The "x" portion of xFIP simply substitutes a pitcher's home runs per flyball rate with the league average (usually about 11 percent), as HR/FB rates have been shown to be inconsistent over time.

So, to summarize:

actual performance

expected performance as expressed in terms of an ERA approximation

No need to get into the math behind xFIP, as many of you are asleep already, but if we take ERA less xFIP, we would come up with lists of pitchers whose:

A. Performance (ERA) is not justified by his strikeout, walk and HR rates.

B. Performance (ERA) should have been better considering his strikeout, walk and HR rates.

Looking at the last 30 days, below are lists of pitchers in both categories. I'll set the cutoff at plus or minus 1.00 in each direction. The first thing you might notice about both lists is the sheer number of pitchers who ended up in the +/- 1.00 ranges. I would venture to guess, and this is a very educated guess, that as we continue to increase the time horizon for this sample beyond the 30 days, the smaller the lists would get, as over time, ERA tends to gravitate toward xFIP as results more closely proximate the underlying metrics (K/9, BB/9, HR/FB).

Category A - Candidate for ERA increase

Mark Buehrle, White Sox(2.74) 4.0 1.7 6.9
Jeremy Hellickson, Rays(2.12) 6.2 3.1 5.3
Jered Weaver, Angels(2.08) 7.4 2.0 6.4
Kyle Kendrick, Phillies(2.08) 4.0 3.0 10.3
Johnny Cueto, Reds(2.06) 5.6 2.6 2.9
Tim Lincecum, Giants(2.04) 8.8 4.0 7.1
Ervin Santana, Angels(1.87) 6.9 1.6 3.2
Fausto Carmona, Indians(1.79) 2.8 2.5 12.0
Charlie Morton, Pirates (1.54) 6.4 4.910.5
Randy Wolf, Brewers (1.22) 5.5 3.1 5.0
Tim Hudson, Braves (1.19) 6.9 1.8 3.7
Josh Beckett, Red Sox (1.16) 8.7 1.612.5
Brett Cecil, Blue Jays (1.14) 6.0 2.313.6
Zack Greinke, Brewers(1.12) 9.6 2.513.6
Luke Hochevar, Royals (1.07) 7.0 2.7 6.9
Blake Beavan, Mariners(1.06) 3.9 1.3 2.7
Ian Kennedy, Diamondbacks(1.02) 8.0 2.1 9.8
Joe Saunders, Diamondbacks(1.00) 4.4 1.3 12.5

Let's look at a few of these pitchers. For the most part, I'm not going to talk about the elite pitchers on this list (Weaver, Lincecum, Beckett, Greinke), as we know what these aces bring to the table.

Mark Buehrle -
It doesn't take a RotoWire subscription to know that Buehrle isn't going to maintain his 30-day ERA of 1.33 for the balance of 2011. Strikeouts have never been a big part of Buehrle's game, so we'll just say that he is what he is - a solid AL-only and spot mixed league option. It's best to expect an ERA in the 4.00 range the rest of the way, right in line with his 4.07 xFIP. Buehrle has made 17 consecutive starts in which he's allowed three earned runs or less.

Jeremy Hellickson -
He's yet to approach the numbers he posted in Triple-A last year (6.0 K/9 vs. 9.5, 3.3 BB/9 vs. 2.7), but that's the difference between the AL East and the International League. That said, he's allowed three runs or less in each of his last eight starts, and, given more experience, a pitcher with his prospect pedigree should show some improvement.

Kyle Kendrick -
The first two words that come to mind here: "smoke" and "mirrors." Maybe being around four other very good pitchers helps, but while he generates a fair amount of ground balls, it's still tough to overcome a relative lack of stuff.

Johnny Cueto -
I don't see Cueto ever being an elite arm, particularly with a 5.5 K/9 and 2.8 BB/9 for the year, but as long as he's healthy, he's probably the Chad Billingsley of the Reds - a solid dependable No. 3 starter and occasionally borderline No. 2. I'm not sure this is a new skill of his, but Cueto has shown marked improvement in his ability to generate ground balls and subsequently minimize home runs. Witness his HR/9 the past four years:

2008: 1.50
2009: 1.26
2010: 0.92
2011: 0.48

He's also seen his strikeout rate decline similarly:

2008: 8.2
2009: 6.9
2010: 6.7
2011: 5.5

All this while maintaining a fastball that sits in the 92-94 range most nights. The only explanation I can give is that he's become more a pitcher than a thrower, sacrificing a few strikeouts in exchange for locating the ball to where hitters are more likely to hit the ball on the ground. His groundball rate has skyrocketed to 53.4 percent this year versus 41.7 percent a year ago, and part of that is due to his ability as reflected in his pitch data to entice hitters to swing at pitches outside the zone. So while the plummeting strikeout rate decreases his fantasy value, it's certainly not hurting his value to the Reds.

Ervin Santana -
One school of thought blames an over-reliance on his slider for Brett Anderson's Tommy John surgery, so I thought I'd mention that no starter in the game throws more sliders than Santana. In fact, no starter relies on a fastball-slider combo more than Santana, who mixes in his changeup just 3.3 percent of the time and doesn't have a documented fourth offering. That didn't stop him from throwing a no-hitter, and in his last 10 starts, Santana has a 1.81 ERA and 63:14 K:BB in 74.2 innings. He's on this list due to the 3.2-percent HR/FB rate recently, but while a few more balls are going to go over the wall down the stretch, he's not going to fall apart, either.

Fausto Carmona -
He's on this list due to an 8:7 K:BB in his last four starts, and we should expect upcoming results to not meet the expectations shown by his recent outings. Translation: don't like him.

Brett Cecil -
I admit I didn't quite get the Shaun Marcum for Brett Lawrie deal for the Jays at the time it went down, but now the Jays have a potentially elite bat locked up cheap for several years, with Marcum set to hit free agency after 2012. The Jays hope Cecil steps up to fill Marcum's shoes, and anyone who tosses a four-hit shutout in Texas gets my attention. That said, Cecil has allowed six homers over his last five starts, a trend that will result in an ERA spike if it continues.

Luke Hochevar -
He screwed the Dodgers over when they drafted him several years ago, so that 5.37 career ERA is well-deserved. All bias aside, there's nothing to suggest Hochevar is anything more than a No. 5 starter now and in the future.

Blake Beavan -
Beavan might end up being the "prize" that comes out of the Cliff Lee deal. Beavan has come in and done well with a 2.83 ERA and 1.09 WHIP in six starts. He makes this list courtesy of a mediocre strikeout rate. He doesn't miss many bats, so when the ball isn't bouncing his way, things are going to get ugly. He's posted quality starts against both Boston and Texas this year, but is that repeatable once those teams' hitters get a hold of more video on him? Not so sure.

Ian Kennedy -
I now believe.

Joe Saunders -
Back-to-back no-hitters and MAYBE I start to believe.

Category B - Candidate for ERA decrease

Tommy Hanson, Braves4.58 11.1 3.7 20.5
Trevor Cahill, Athletics3.43 7.9 5.1 11.1
Gio Gonzalez, Athletics 2.78 10.4 4.6 5.0
Jonathon Niese, Mets2.75 9.5 1.9 10.5
Jordan Zimmermann, Nationals2.73 9.3 1.2 14.3
Brian Duensing, Twins 2.60 6.6 1.5 20.6
A.J. Burnett, Yankees2.49 8.9 4.3 17.2
Paul Maholm, Pirates2.47 6.2 2.1 12.0
Derek Lowe, Braves2.46 4.8 4.1 9.5
Carl Pavano, Twins 2.41 3.6 2.1 7.1
Bruce Chen, Royals2.27 5.4 3.7 15.6
Livan Hernandez, Nationals2.06 4.6 1.9 16.7
Brad Penny, Tigers1.87 2.3 3.0 6.9
Jordan Lyles, Astros1.84 5.3 0.6 11.1
Brett Myers, Astros1.73 8.2 1.6 18.2
Chris Capuano, Mets1.60 6.7 3.2 9.5
Chad Billingsley, Dodgers1.54 7.5 3.4 3.3
Anibal Sanchez, Marlins1.52 9.4 1.7 12.1
Jason Vargas, Mariners1.50 5.2 3.3 11.9
Tim Wakefield, Red Sox1.34 6.3 2.0 16.7
Brandon Morrow, Blue Jays1.30 10.0 2.6 12.5
Ryan Dempster, Cubs1.16 9.9 3.4 3.3
Ricky Nolasco, Marlins 1.13 6.8 2.3 11.1

Tommy Hanson -
The Braves received good news this week on Hanson, as his shoulder shows only mind tendinitis. For all his struggles (nine HR in six starts), Hanson is still missing plenty of bats, so once the injection he received in the shoulder does its magic, expect better results in terms of ERA. Trade for him, if possible.

Trevor Cahill -
A .384 BABIP isn't helping, but Cahill also is averaging just 89 mph on his fastball this year and 88.4 mph over the last 30 days. That's down about two mph over last year's version, and when you mix in some poor control, it's hard to get too optimistic.

Gio Gonzalez -
Still too many walks, but whenever I see him pitch, I think "this is a guy who could throw a no-hitter any day."

Jonathon Niese -
Only four pitchers in the game throw their curve ball more often, and like the rest, it's command of that offering that appears to be the key to success. I caught some of his last start against the Braves, and he was catching far too much of the plate, resulting in 10 hits in five innings. All in all, Niese has a 4.12 ERA, 7.9 K/9 and 2.6 BB/9. Good stuff there.

Brandon Morrow -
Morrow has been on this side of the ledger the last two years, posting xFIPs in the 3.50 range and ERAs a full 1.00 higher. Still, I'll take anyone who has shown the ability to consistently post K/9s in the 10-plus range, with the hope that they'll figure out how to overcome their weaknesses. For Morrow it's been control, which he's improved on this year significantly (3.3 BB/9 vs. 4.1 a year ago). Like Gonzalez above, Morrow is a strong no-hitter candidate.

Paul Maholm -
I'm a huge advocate for the job that Pirates pitching coach Ray Searage has done this year. It's not like the Pirates added Cliff Lee, so the fact that the pitching staff has gone from the league's worst (5.00 ERA in 2010) to the league's No. 10 staff with a 3.71 ERA is a direct result of coaching. Maholm has struggled in three of his last four starts and somehow allowed seven runs in 6.2 innings against the Padres, but he's really pitched better than that and is a solid deep-league mixed option.

Derek Lowe -
If it weren't for his $15 million salary, Lowe would probably be on the waiver wire with Julio Teheran in the rotation. Lowe has clearly suffered a degradation in skills this year.

Chris Capuano -
Teams pick guys up off the scrap heap every year, and once in a while they hit. The Mets certainly have with Capuano, who has struggled lately but still has a 7.4 K/9 and 2.8 BB/9. Capuano hasn't been fantasy-relevant since 2006, but despite the obvious flaws (lack of "stuff"), Capuano is still a quality NL-only pitcher.

Anibal Sanchez -
Sanchez has a 5.12 ERA in his last three starts, but in his last five, he has a 33:6 K:BB in 31.2 innings. That's enough for me to proclaim that he will be a 3.50ish ERA pitcher the rest of the way.

Ryan Dempster -
Dempster's place on this this list is really a product of one ugly outing against the Phillies and another in which he walked six batters , but he's still recorded quality starts in each of his last three outings. Expect his current performance level to continue.

Regan, a four-time Fantasy Sports Writers Association award winner, was named the 2010 Fantasy Baseball Writer of the Year.

Follow @vtadave on Twitter.