Do the Twins need an Ace?

The Conventional Wisdom right now among the chattering classes is that the Twins absolutely need to get an "Ace" pitcher if they want to compete in the playoffs this year, or even make it to the playoffs for that matter. I heard this very thing on MPR on Tuesday morning from Howard Sinker, the Star Tribune's Twins blogger. There are many things about what Howard Sinker had to say in that interview that I fundamentally disagree with but the most egregious, in my view, is his complete lack of respect for the performance of one of the Twins starting pitchers. From the interview:

Four fifths of the starting rotation, really everybody except for Carl Pavano, has flown off badly in one way or another.

This was said in the context of discussing who was under performing on the team. What "flown off badly" means I'm not exactly sure, but to completely disregard the first half performance of Francisco Liriano would fall into the same category of "flying off badly."

Here's the stats of the entire Twins staff, the standard baseball stats everyone is familiar with and WHIP, walks + hits per inning, which is starting to be published in newspapers more often these days (all stats used in this post were as of the All Star break).



So right off the bat we can see that Howard Sinker doesn't know what he's talking about. Clearly Nick Blackburn has been terrible, but Scott Baker and Kevin Slowey have both been decent enough, they are on pace for about 200 innings of sub 5 ERA baseball. While that is not world beating, it is certainly acceptable from your third and forth starters. What you can see even looking at the standard stats though is that Francisco Liriano is at least the Twins second best pitcher and other than the fact that he has a losing record, is doing at least as well as Pavano. And about that losing record, in case there's anyone who thinks wins actually mean anything, here's a graphic you should see.



Guess who got credit for the win in that game and I'll give you a hint, it wasn't Liriano. There are many, many discussions on the internet about the uselessness of the win stat in evaluating pitching performance, but leave it to the traditional sports media to completely ignore all of the work going on in the field of baseball stats these days and instead rely on outdated methods of judging player performance.

Here is a comparison of Carl Pavano and Francisco Liriano using some different metrics.



If you don't know what some of these stats are, that's fine, I'll explain them or at least attempt to. The first two are strikeouts (K/9) and walks (BB/9) per nine innings and the one after that is strikeout to walk ratio (K/BB). What we see here is that Liriano is striking out significantly more batters than Pavano and Pavano is walking fewer batters than Liriano. This gives them essentially the same K/BB ratio; it's getting into the next series of numbers where the two pitchers start to really diverge, before we get can do that however, we must define a few concepts.

The most import one to understand is a concept called "regression to the mean". Simply stated this means that if a player has been in the big leagues for eight years and is a career .280 hitter, but this year he's hitting .330, we can expect that his batting average going forward will regress to his mean of .280. This is not a baseball concept; it is a statistics concept that has applications in predicting future performance, in this case for baseball players.

Also important to understand are a few of these advanced stats and what they mean; first BABIP, batting average on balls in play (from Baseball Prospectus):

Based on the research of Voros McCracken and others, BABIP is mostly a function of a pitcher's defense and luck, rather than persistent skill. Thus, pitchers with abnormally high or low BABIPs are good bets to see their performances regress to the mean. A typical BABIP is about .300.

This is an import concept that sometimes people have a hard time accepting, but what it means is that once a batter makes contact with a pitch there is nothing the pitcher can do about it anymore, it is out of the pitchers control weather that batted ball will fall for a hit or not. In other words there's nothing pitchers can do to prevent hits other than not letting batters make contact.

Another important stat that's related to this concept is FIP, fielding-independent pitching, a metric that forecasts a pitchers ERA based on their peripheral stats (from Hardball Times):

Fielding Independent Pitching, a measure of all those things for which a pitcher is specifically responsible. The formula is (HR*13+(BB+HBP-IBB)*3-K*2)/IP, plus a league-specific factor (usually around 3.2) to round out the number to an equivalent ERA number. FIP helps you understand how well a pitcher pitched, regardless of how well his fielders fielded.

What we can see by looking at the BABIP's of the two pitchers is that up to now Liriano has been exceptionally unlucky on batted balls while Carl Pavano has been exceptionally lucky. As the season goes on we can expect these numbers to regress to the mean of .300, meaning Liriano should give up fewer hits and Pavano should give up more.

This is supported by FIP, where Liriano is sporting a league best 2.18. That's league best as in all of Major League Baseball best; number two is Josh Johnson at 2.31 and number three is Cliff Lee at 2.58. That's Cliff "we absolutely must trade for him if we want to win a championship" Lee. You can also see by looking at the difference between his ERA and FIP (E-F) just how well he's doing compared to what his ERA says and just how badly his ERA is under valuing his performance to date.

The last metric is WAR, Wins Above Replacement, which is an estimation of how many wins a player adds versus a replacement level player, usually defined as an average AAA player. In that metric Francisco Liriano is currently third in all of baseball, behind only Roy Halladay at 4.6 and Josh Johnson at 4.4, again ahead of Cliff Lee who's at 3.8. If you also consider that the Twins are paying Liriano less money than Pavano, or any of those other pitchers for that matter, there is absolutely no question who the most valuable pitcher on the Twins staff has been so far this year and just how badly off the mark Howard Sinker is.