At Yankee Stadium tonight, Joba Chamberlain finally makes his long-awaited first Major League start, after months of name-calling and top-secret arm-stretching. Three hours later, and 3,000 miles away, Pedro Martinez finally returns to the mound for the Mets in San Francisco, making his first start since injuring his hamstring in his season debut April 1. Both the Yankees and Mets have shown signs of life lately, but the fact remains they’re both still hanging around the .500 mark, so with a third of the season already in the books, expectations are high that Joba and Pedro will be the white knights that ride into their respective rotations and save the season.

But neither team should start printing playoff tickets quite yet. Pedro’s started just six games in past twenty months, and there’s no telling whether he can easily slide in as a bona fide No. 2 starter — and stay there without getting hurt again. Then there’s Joba, who besides being limited by low pitch counts in the short term, will be experimenting with an expanded pitch repertoire. Also, to reiterate, he’s never started a Major League game before. (Even Mariano Rivera has cautioned against considering Chamberlain the team’s savior.) Whether it’s smart to pin a team’s hopes on an injury-prone 36-year-old or a barely tested 22-year-old remains to be seen, but except for Phil Hughes’s expected return in July and the possible late-season return of Orlando Hernandez, this is pretty much it for reinforcements. As far as the Yankees and Mets are concerned, the season starts — again — tonight. —Joe DeLessio