Last week, talking with Todd Wright on Sporting News Radio, I got off on something of a rant about calling Zack Greinke the best pitcher in baseball. It’s not unfair to say that he’s pitched the best in 2009, but the title mentioned implies a longer list of qualifications. It’s similar to my argument about All-Star teams: the last two months of work is information, but it’s a fraction of the information necessary to render a decision on selecting squads for the Midsummer Classic.

This week, it’s Roy Halladay whose name keeps popping up. Halladay, of course, has greater claim to the title, not only pitching wonderfully this season but in most seasons this decade. In Tuesday’s chat I got asked, “Is Roy Halladay baseball’s best pitcher?” My answer:

I still have Johan Santana atop my list, and I think you can argue that Halladay is the best of the next group down, which would include Brandon Webb, CC Sabathia, and Tim Lincecum. Santana is a bit like Albert Pujols now, where he’s so good people look for other guys to talk about.

I was thrilled to draw Johan Santana on my first trip to CitiField, and if the results weren’t very impressive, he at times showed just why he’s the best pitcher in baseball, He kept the Phillies off balance, getting a lot of popups, and pounded the strike zone early in the count to make his changing speeds that much more effective late. It’s a small point, but Santana also bluff-bunted and smacked a game-tying double down the right-field line, and speared a line drive for an inning-ending double play. Like Greg Maddux, Johan Santana isn’t just a pitcher; he’s a baseball player.

Maybe Webb, who hasn’t pitched in two months, should be left out of the conversation until he does once again. He’s clearly a candidate for the title, but in a field this deep, the questions about his shoulder are enough to keep him out of the mix. Here is what the other four guys have done so far this season:

Pitcher        ERA    IP    BB   SO   HR   SNLVAR   VORP   PRAR
Santana       2.39   79.0   22   91   10     2.4    20.6    26
Halladay      2.52  100.0   12   88    6     3.6    36.3    32
Sabathia      3.56   86.0   27   61    6     2.0    20.7    22
Lincecum      2.96   79.0   25   95    3     2.2    19.9    18

What jumps out at me here is how much better than the field Halladay has been this season. Before looking into the numbers, I had thought that his edge on Santana was much smaller than this. Throwing 20 percent more innings in a tougher run environment, however, makes him nearly twice as valuable as Santana and Lincecum (and Sabathia, whose surface stats are not as impressive).

There is a problem with the above analysis, though. The park factors used in calculating the run environments of Santana and Sabathia for purposes of the metrics are based on a third of a season in their teams’ new parks. That’s not terribly reliable. It is entirely possible that the adjustments we’re making for run environment are inadequate, or even wrong. I doubt any adjustment changes the conclusion that Halladay is the man so far this season. It’s just worth keeping in mind that all metrics for Yankee and Met players are going to be problematic until we have a firm handle on the new parks’ impacts.

What did these four look like a year ago?

Pitcher       ERA    IP    BB   SO   HR   SNLVAR   VORP    PRAR
Santana      2.53  234.1   63  206   23     8.5    73.6     79
Halladay     2.78  246.0   39  206   18     7.6    70.6     76
Sabathia     2.70  253.0   59  251   19     8.7    77.4     84
Lincecum     2.62  227.0   84  265   11     8.6    72.3     80

Sabathia was famously the best pitcher in baseball a year ago, a distinction that got him less Cy Young consideration than he deserved because of the problems a player who splits his year across leagues presents. Halladay was fourth among this group last year, although close enough to the others that you have to acknowledge the difficulty of his slate-he sees an awful lot of tough lineups in the AL East-relative to the other three. Halladay faced the second-highest quality of batters (as measured by OPS) of any qualifying starter last year. Eleven of the top 20 in this category pitched for AL East teams. His job is just harder than the job of the other candidates. (In 2009, Halladay is 52nd in this category among 116 pitchers with at least 50 innings pitched.)

Take it back a year, as 2007 performance should carry some weight in this discussion.

Pitcher       ERA     IP   BB   SO   HR   SNLVAR   VORP    PRAR
Santana       3.33  219.0  52  235   33     6.4    57.1     72
Halladay      3.71  225.1  48  139   15     6.7    49.9     43
Sabathia      3.21  241.0  37  209   20     6.5    67.7     72
Lincecum      4.00  146.1  65  150   12     3.8    26.0     29

Lincecum was called up in May, so this comparison won’t go well for him. Halladay leads in Support-Neutral Value, yet trails by a bunch in the other two metrics, which I think is an AL East thing. Sabathia, all things considered, was probably the best in 2007.

If you take the analysis back further, Santana opens up a huge lead. Lincecum wasn’t even a professional, Halladay missed big chunks of 2004 and 2005, and Sabathia wasn’t at this level until 2006. I think some weight needs to be put on performance that far back, but not very much, so it’s extra points for Santana, rather than the whole ball of wax. Let’s total up the last three seasons to see where we are. Actually, we’re going to count 2007 at 2/3 of the actual numbers, and 2008 and 2009 at face value:

Pitcher       SNLVAR     VORP     PRAR
Santana        15.1     132.2      153
Halladay       15.6     140.1      136
Sabathia       15.1     143.3      154
Lincecum       13.4     100.9      107

We can comfortably remove Lincecum from the discussion until the end of this season, as his track record is a bit too short to compete with the other three The data is mixed on the others, with Sabathia on balance having the best stats of the group. Since he’s also having the least impressive 2009, that doesn’t help a whole lot. Are we missing anyone? Zack Greinke’s stats aren’t going to be much better than Lincecum’s. Jake Peavy‘s missed starts last season hold down his numbers. Roy Oswalt isn’t quite the same guy he was a couple of years ago. Dan Haren is four months shy of competing for the honor. Justin Verlander wasn’t good last year.

There’s definitely room to consider that Halladay, and now CC Sabathia, have tougher jobs than the other two. They’re just going to see a better set of hitters than Santana and Lincecum will because of the AL East’s quality and the unbalanced schedule. Is that worth five runs a year, or 15, or 30? We’re guessing a bit, and at that, we don’t know how the starts will fall; you can pitch in the AL East, but get lucky and make fewer starts in the division than perhaps you should. The Opponents’ OPS report is a decent proxy for this sort of thing.

It turns out that it’s not Santana who is being shortchanged, but Sabathia. He’s been just as good as Johan Santana and better than Halladay during the survey period; he was more durable, though less effective, than Halladay in 2006, and comparisons between the two prior to that are involving guys who weren’t qualified for the title based on effectiveness and durability. On the other hand, he’s slipped a bit in a dozen starts to date, which is admittedly a thin thread to on which to attack his case. Halladay has stronger peripheral stats this season and the highest batting average on balls in play, suggesting he’s been the least lucky of the group.

Sometimes it’s about the journey rather than the destination. After all of that, I’m no closer to knowing who the best pitcher in baseball is than I was whe I started. Santana hasn’t had the edges, the run prevention, to warrant my full-throated defense if the idea that he is still the best pitcher in baseball. On other other hand, I take these labels seriously, and would like to hang the honor on the right person. In this case, however there is no right person. All three pitchers have have a reasonable claim to the title of “best pitcher in baseball.” The rest of 2009 will help us settle the argument.