Dan Haren takes the mound tonight as the MLB ERA leader, tied with Jake Peavy at 1.64. Both pitchers have allowed only 11 earned runs in 60 1/3 innings.

Haren has posted some very, very good numbers so far this season. Among starters, his VORP of 19.9 is the best in the AL, while his WHIP of 0.96 is the only AL mark under 1.00. Haren's 3.43 SO:BB ratio is the ninth best mark, just behind Joe Blanton -- more on his return to success later.

There is one thing that bothers me about Haren's success, though. His BABIP is a bit low -- to the point where I'm convinced that Haren is due for a return to the norm, and it will appear that he's not pitching as effectively as he was in April and May.

Haren's BABIP sits at .237, well below his career average of .292 and the accepted MLB average of .290. That suggests that he's getting lucky on where balls in play are falling -- i.e., they're being hit right at fielders, and aren't finding the gaps at a normal rate.

Of course, you could probably have guessed, using nothing more than a gut feeling, that a 1.64 ERA is unsustainable over anything more than a month or two. Since the pitcher's mound was lowered after 1968, there have been only three pitchers who've qualified for the ERA title with an ERA as low as Haren's. Greg Maddux in 1994 (1.56) and 1995 (1.63), and Dwight Gooden in 1985 (1.53). Furthermore, only seven times has an AL pitcher had a sub-2.00 ERA in that ERA.

Apparently 1971 and 1972 were very good years to be a pitcher.

Now, I'm not prognosticating a precipitous decline for Haren, but I'd guess you'll soon see a few more games where he gives up three earned runs than one or zero. Speaking of which... these are the number of earned runs given up by Haren in his nine starts this year: 0,1,3,0,1,2,2,2,0. And the 3 was against the Yankees.

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Now, on to Joe Blanton's return to form that I mentioned before. In his minor league career, Blanton struck out nearly 5 times as many batters as he walked, at the rate of almost one per inning. In his first three MLB seasons, he walked twice as many and struck out 40% fewer. As I've touched on before, the difference between his apparently great rookie season and apparently mediocre sophomore season came down to a huge difference in BABIP.

Now, it appears that Blanton is back to being the pitcher he was in the minor leagues. His rates this season are strikingly similar to his MiLB numbers:

While Blanton's developing 2007 campaign isn't quite as good as his minor league career, it's a far cry from his career thus far in the Show. You can't expect a pitcher to have the same level of success at the majors, of course, but he's now pitching much more like Blanton the River Cat than Blanton the A.

Oh, and about that pesky BABIP problem Blanton had? It's now a very reasonable .275, something that leads me to believe that this might be the real Joe Blanton.