Mackey: Scott Diamond has been good, but let's not get carried away
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Generally speaking, we tend to measure success for starting pitchers based on whether their ERA starts with a 3 and whether they came close to throwing 200 innings.
There are, obviously, many other factors that go into long-term success as a starting pitcher. Strikeouts, walks, home runs allowed and hits allowed all enter into the equation at some point, and for the sabermetric geeks (like myself), we tend to analyze groundball rates, defense-independent metrics and other items that help to weed out luck. I still refuse to acknowledge wins and losses as a valid measurement for pitcher success.
But if a starting pitcher finishes a season throwing close to 200 innings with an ERA that starts with a 3, it's fair to say he had a pretty solid season.
Per those guidelines -- or per any guidelines, really -- the Minnesota Twins have not had very many solid seasons from their starting pitchers lately.
Since Johan Santana was traded five seasons ago, only twice has a Twins starter posted an ERA below 4.00 while also throwing at least 175 innings. Those pitchers were Francisco Liriano and Carl Pavano in 2010, and both did it in 2010.
Think about that.
Those are some pretty modest guidelines -- 175 innings and a sub-4.00 ERA during a time when the average American League starter ERA was 4.21 last season and 4.26 in 2010.
Yet, in 2008, 2009 and 2011, no Twins starter could meet those guidelines.
Because of this starting pitching deprivation, it's easy to overreact and use the term "ace" when someone like Scott Diamond pitches well over an extended period.
In the American League Central, Chicago White Sox starters have accomplished the feat seven times over that same stretch (John Danks three times, Mark Buehrle three times, Gavin Floyd once). Detroit Tigers starters have done it seven times as well (Justin Verlander four times, and Max Scherzer, Edwin Jackson and Armando Galarraga each once).
Even the Kansas City Royals (Zack Greinke, Gil Meche) and Cleveland Indians (Cliff Lee, Fausto Carmona, Justin Masterson) have done it three times each over the past five years.
Los Angeles Angels and Tampa Bay Rays starters have each done it a combined 18 times.
Posting a 3-something ERA was a bit more difficult when hitters were bursting out of their elastic-sleeved jerseys in the late-1990's. But in 2012, there are 54 qualified starting pitchers in the major leagues with sub-4.00 ERAs and 17 with ERAs under 3.00.
It might as well be labeled as the second coming of the dead-ball era.
And considering 39 pitchers threw at least 200 innings last season, crossing the 175-frame threshold isn't asking much.
As bad as Twins starting pitchers have been over the past two seasons, Diamond has emerged as a reliable arm. Despite spending all of April at Triple-A Rochester, Diamond is on pace to flirt with that 175-inning mark, and it'd take a massive implosion for him not to post a sub-4.00 ERA.
Internally, the Twins did not expect the type of production Diamond has provided, especially considering his struggles in Triple-A last season. But any skepticism within the organization about the legitimacy of Diamond's early-season performance mostly wore off after he shut down the Reds in Cincinnati in late June and the Tigers in Detroit in early July.
Twins decision-makers don't view him as the staff ace of a playoff-caliber team. But in 19 starts, Diamond has completed at least six innings 17 times. His shortest outing is 5 1/3. At the very least, even if hitters figure him out to a certain extent, Diamond has proven to be a workhorse.
Fielding Independent Pitching (FIP) helps tell us what a pitcher's ERA is likely to be over the long haul. Diamond's 3.84 FIP and 3.68 xFIP both suggest his 2.95 ERA is likely to jump up a bit, because since 2008 -- among pitchers who have thrown at least 400 innings -- only Tim Hudson and Joe Saunders own ERAs that have outperformed their FIPs (or xFIPs) by more than a half a run.
But if the Twins have found a pitcher who can sustain a sub-4.00 ERA for 175-plus innings going forward, it's a step in the right direction.
For a mid-rotation starter. Not an ace.