Josh Johnson and Ubaldo Jimenez: tied, for now.

Ubaldo Jimenez has had, without a doubt, the most spectacular season of any starting pitcher in the major leagues. You know about the no-hitter, of course. And shiny-number devotees worldwide marvel at his 14 wins, all collected prior to the beginning of July. Yes, Jimenez has put together quite a nifty half-season. And yet, quietly, Josh Johnson has sneaked into a tie atop the major league ERA leaderboard at 1.83.

As you might expect from players with matching ERA’s in July, Jimenez and Johnson have been similarly excellent. Each has made 16 starts, and Jimenez has faced that many more batters thus far. Jimenez has also managed to finish what he’s started three times, while Johnson has yet to notch a complete game. Throw in the flashy headlines, and it’s easy to think Jimenez is having the best pitching campaign in a season rich in such things.

But that’s not the case. Johnson has the edge over Jimenez in strikeouts (107-102), walks (27-40), and home runs surrendered (4-5). Now, obviously these differences are somewhat negligible; you really have to pick nits to differentiate two starters having such excellent seasons. But nit-picking is exactly the sort of pursuit a lazy, pre-holiday afternoon at the office is for! Indeed, I think the real question here is which of the two figures to stay this good for the duration of the season.

Johnson again shines. Taking a quick glance at xFIP, Johnson (3.16) has been extraordinarily lucky to a lesser degree than Jimenez (3.68). It’s fairly telling that, of the two ERA leaders, Johnson has an xFIP inferior to studs Francisco Liriano and Roy Halladay. Jimenez, should he look at his place in the xFIP standings, will notice names like Hiroki Kuroda and Jered Weaver between he and the top of the leaderboard. That’s nothing to sneeze at, to be sure, but it’s clear that his performance is even more luck-driven than Johnson’s. So far, at least.

Where Jimenez has a clear advantage as far as staying power goes is in durability. He’s coming off seasons of 198.2 and 218.0 innings, while Johnson’s 209.0 inning 2009 campaign was preceded by an injury-shortened 87.1 inning 2008. We all have our own opinions about the famed Verducci Effect, but I think we can agree: an innings increase of over 100 in a young pitcher is a big, fat red flag. Pitchers are unique creatures, of course, and everyone outside Braves- and Phillies-land hopes Johnson can handle a full season. And maybe he can.

It seems to me that, in picking one of these thoroughbreds in a two-horse race for the rest of the season, you’re stuck with a conundrum. Johnson probably has the edge in the rate stats; his 5 strikeout lead isn’t much, but a walk less per start really matters. Jimenez does have a slight edge in ground ball rate, but his BABIP is .15 lower than Johnson’s .270 measure of luck. But rate stats only tell part of the story. Johnson’s inferior track record when it comes to durability means you pick him at your own risk.

Of course, the point here isn’t necessarily to pick one. Really, both have been spectacular thus far, and we hope they stay dominant. Odds are against that, though, so let’s narrow the scope: in a year of pitching anomalies, Johnson and Jimenez have put up similarly excellent halves, but at much different volume levels. Maybe Johnson shuts down the Braves tonight and makes some noise of his own.