Jason Hammel kind of had a rough time of things on Wednesday night against the Blue Jays, giving up four home runs in the Orioles 4-1 loss. Hey, at least he had a better night than the Rangers’ staff, am I right? But even after last night’s poor start, Hammel’s ERA is still an excellent 3.06 (3.52 FIP), up from 2.78 (2.71 FIP).

Although Baltimore has been showing signs of team-wide regression during their current five-game losing streak, they are still tied with the Tampa Bay Rays for first place in what is currently a very tight American League East.

Obviously, much of the credit has to go to Adam Jones’ impression of Matt Kemp and Wei-Yin Chen’s pitching, but Hammel has been a very nice surprise since coming over to Baltimore in the Jeremy Guthrie trade. Let’s take a look at how the right handed starter has done it, and see if we can’t figure out whether or now he can keep it up.

While Hammel does seem to be pitching better than he ever has at any time in his career, it is not as if he has never pitched well before. He’s currently striking out batters at a rate far better than any other in his career, but while his good (7.6 percent) 2012 walk rate is better than his average-ish 9.2 percent from 2011, he had displayed even better control in his first two years in Colorado.

Indeed, just looking at FIP and adjusting for park, Hammel was actually quite good in 2009 and 2010 for Colorado, at about four wins above replacement each season. He combined an average strikeout rate with good control in a very tough run environment, with Coors Field still being the most hitter-friendly park in baseball, even with the humidor.

Still, it is fair to say that based on statistics, Hammel seems to be pitching better than he ever has. But are the changes that have led to this success lasting? Well, that is hard to say. As was implied above, if one simply looks at ERA and/or his 2011 season, one sees a greater juxtaposition between his current seasonal line and prior performance. On the other hand, if one looks at his peripherals in 2009 and 2010, the current season does not seem as surprising.

However, there are some improvements worth mentioning. For one, Hammel’s strikeout rate has taken a big jump. For another, Hammel’s ERA is almost half a run better than his FIP.

That is quite atypical for him. His ERA and FIP were about identical last year, but for his career his ERA has been significantly higher than his FIP. In a small sample, I usually will go with FIP, and while 793 career innings itself is not a huge sample, it might be that Hammel is one of those pitchers who is a “true talent” FIP underperformer.

The easy thing for the binomial saberist to say at this point is that while Hammel has given us a nice bit of additional data, the preponderance of his past performance compared to the current season sample, his apparent luck so far in 2012 in stranding runners (about 81 percent, league average is usually around 72 percent), and, above all, our old friend regression, we would expect Hammel to “come back to earth” (last night being the beginning) fairly quickly.

And, indeed, a big part of me tends to think that will be the case. However, I want to move beyond that for now and “fog the measure” (ahem) a bit with a few short suggestions of why it is not that easy in Hammel’s case.

First and perhaps foremost, it seems that Hammel has added a new pitch.

This is probably easiest to see on FanGraphs player page Pitchf/x pitch type section, which notes a much higher number of two-seam fastballs this year. Brooks Baseball’s player page for Hammel uses slightly different Pitchf/x classifications, and shows that Hammel pretty much added an entirely new “sinker” this season. Harry Pavlidis, who is in charge of Brooks’ classifications, has already written about Hammel’s success with the new sinker. But this goes beyond simply an improved groundball rate for Hammel. According to Brooks, He is also getting more whiffs with the two-seamer this year than he did with the four-seamer in previous years, and his four-seamer is also more effective in missing bats so far this season.

Now, does this mean we throw out regression and prior seasons because Hammel is a “new pitcher?” I do not think so, but it has to be taken into serious consideration. This sort of qualitative, “objective scouting” analysis is where the real cutting-edge sabermetric research is at. If it is not exactly clear how it should be integrated into true talent projections, it has to be taken into account.

While there are other factors to consider with Hammel, I want to add just one more cloud of fog: the nature of the team-switch.

Now, the effect of Coors Field is often overplayed, especially when talking about hitters. Moreover, while getting out of Coors probably helped Hammel, he also no longer gets to face pitchers, which somewhat “cancels out” the benefits of moving out of the tough run environment in Colorado.

Still, while Camden Yards is not exactly the place bats go to die, compared even to post-humidor Coors Field, it is much more pitcher friendly. But beyond simply the overall run environment, Coors Field is different enough from most parks with its inflation of every kind of hit (most parks will, for example, inflate home runs at the expense of balls in play, or the other way around) that the the gap between Hammel’s ERA and FIP from those seasons may not be simply transferable (as if any such thing were “simply transferable”) to his true talent in the context of the Orioles.

Jason Hammel is having a nice season for the Orioles. More likely than not, he is going to regress closer to league averages. However, beyond the raw numbers, his new pitch and a new park leave greater room for doubt than usual about exactly how much that regression will end up being.