Jon Shepherd: Does Chris Tillman qualify as an ace?

Should we now be referring to Chris Tillman as an ace? Well, it depends on what you mean.

In the past, I have found that the most contentious part of the discussion is trying to define what it means to be an ace. Some like to think an ace is the best pitcher on a team, but that definition has some trouble. For example, think about the Diamondbacks with Curt Schilling and Randy Johnson. They certainly were both aces. Others like to think of an ace as being one of the best 30 pitchers in baseball, as in one for each team, but why exactly should we think that there are always 30 aces at all times in baseball? I would think that, like anything, there would be lean times and robust times when it comes to pitching.

Personally, I tend to use the definition that several scouts I know use: An ace is a pitcher who consistently provides elite performance. Using that as a definition, you wind up with anywhere between five to 10 aces in all of baseball. Why? Lots of pitchers wash in and wash out of elite performance. Very few arrive at that level and stay. When you want to discuss a pitcher who is an ace, you want to be sure of that elite performance, as opposed to someone who simply has the potential of elite performance. That is a rather selective definition and it probably should be.

Moving forward, you can use a few different ways to declare a pitcher an ace. You can ask evaluators or look at the numbers. What do the evaluators think? My unscientific polling found agreement on Clayton Kershaw, Felix Hernandez, Yu Darvish, Chris Sale, Max Scherzer and David Price. They thought there were certainly other good pitchers, perhaps ones that used to be in their minds an ace (e.g., Adam Wainwright), but that was their current view.

From the scout side, you never hear about Tillman in the discussion. As he was coming up through the minors, he had potential for a plus fastball and a plus curveball. However, he lost his velocity on his fastball and he has trouble with his curveball command. He is largely considered a good mid-rotation arm and nowhere near an ace.

If you wish to go after advanced metrics, you might use something like fWAR, a holistic statistic that leans heavily on events that a pitcher can control (such as strikeouts, walks and home runs). Using that metric, we would consider a pitcher with an fWAR over five wins to be an elite pitcher. To average that over four seasons might be considered ace-worthy. That would give you Kershaw (18.1 fWAR), Hernandez (17.3) and Scherzer (15.9). Pitchers who might make that level as the season winds down include Justin Verlander (14.8), Sale (14.8), Price (14.3), Wainwright (14.1) and Darvish (14.1). Those two lists are actually fairly similar with only Verlander and Wainwright added to the mix. The highest-rated Orioles pitcher over that time is Wei-Yin Chen at 6.1 fWAR. Tillman is at 5.3 fWAR.

Again, fWAR likes to look at strikeouts, walks and home runs (among other things). With those measures, Tillman looks worse than average. Tillman's 7.07 strikeouts per nine innings over the past three seasons is 78th^-best out of 130 pitchers with a qualified number of innings. His 2.90 rate of walks per nine innings is 87th^-best. His 1.19 rate of homers every nine innings is 112^th overall. However, his 3.45 ERA over that time period is 34th-best, which is about 20 percent better than those three previous figures would suggest (4.26 FIP).

What would account for those differences? Well, a great defense could work wonders on a pitcher's ERA. If we look at the Orioles defense over the past two and a half years, we see the club is worth about 70 runs saved per season. Tillman would be seeing about 12 runs saved personally. If you add those runs back in, he has a 3.69 ERA. That only accounts for 25 percent of the difference in expectation versus actual result. That other 75 percent may be either that Tillman can do things that we cannot measure very well or that he has had an amazing string of luck. With the time frame being two and a half seasons, I lean toward the ability side over the luck side.

In the end, Tillman is a kind of pitcher who has shown he can do more than he seems capable of doing. In time, he may be considered an ace, but he will need to continue to be successful year in and year out to earn that distinction. Unlike others with loud tools, he will not simply be given the ace moniker.

Jon Shepherd blogs about the Orioles at Camden Depot. Follow him on Twitter: @CamdenDepot. His thoughts on the O's appear here as part of MASNsports.com's continuing commitment to welcome guest bloggers to our little corner of cyberspace. All opinions expressed are those of the guest bloggers, who are not employed by MASNsports.com but are just as passionate about their baseball as our roster of writers.