Mike Pelfrey’s 2010 success is all the rage these days in the blogosphere and local papers, and probably comes as a surprise to all those who raged over his mostly defense-induced struggles from 2009.

So what’s made the difference? No surprises, really: Pelfrey’s getting a bit lucky, benefiting from a better defense, and using his new splitter to induce more weak contact and swinging strikes than ever before.

Big Pelf has yielded a .279 batting average on balls in play, well below his career .311 rate. That’s at least partly due to a slight uptick in Pelfrey’s trademark groundballs — he’s now inducing 52.5 percent, up from a career 50.3-percent rate. It also can’t hurt that the Mets’ defense has played, statistically, significantly above average this season after being third worst in the Majors last year.

Still, while Pelfrey is certainly enjoying the return of Jose Reyes behind him, it’s probably unreasonable to expect him to continue yielding so few hits. At some point, a few more balls will drop in or squeak by defenders.

The good news is Pelfrey’s better prepared to handle that situation because he’s missing more bats. The big Kansan will never be Tim Lincecum, but he’s striking out 6.5 batters per 9 innings, more than a full batter more than his career average.

That’s good, and likely largely due to Pelfrey’s new splitter. The pitch has been, on average, his most effective offering this year. It will be interesting to see if hitters learn to lay off the ball as it dives out of the zone once the new-look Pelfrey has been around the league a couple of times, but at the very least the effective splitter must make Pelfrey’s heater a bit more difficult to time.

All the fancy stats — FIP, xFIP and tRA — show that Pelfrey’s been pitching significantly better than he ever has before. That’s no stunning insight, of course, but the stats seem to indicate real improvement and not plain luck or random fluctuation.