The biggest problem the Red Sox have had these last couple of years is that their starting pitching has continued to let them down.

No surprise: The biggest reason why the Sox are off to such a good start (8-4) is that their starting pitching has been nearly off-the-charts terrific.

Yesterday, Ryan Dempster became the latest starter to post a lights-out performance, and even though new closer Andrew Bailey blew a save, the offense was there to save the day in the end.

Mike Napoli’s walkoff RBI double in the ninth inning meant a 3-2 win, a three-game sweep of the Rays and a reason to believe in the 2013 Red Sox: It’s all about the starting pitching, and so far they have had that in spades.

“Really, throughout this homestand, our pitching has been exceptional, starting pitching has been outstanding,” manager John Farrell said following the conclusion of the 4-2 homestand. “(Excellent starting pitching) sets the tone. We haven’t clicked (Nos.) 1-9 offensively. To have the game in check, low-run games, we’ve talked about the importance of starting pitching. Really, that being a cornerstone of how far this team will go, not getting too far ahead of ourselves, but through 12 games, they’ve set a very good tempo, a very good tone to every ballgame we’ve played.”

Dempster (0-1. 2.65 ERA) had his first stellar outing for the Sox, giving up just two hits in his seven innings, the first time in three starts he’s been able to pitch past the fifth. His last start was scotched early because of rain, but on this sunny day he looked every bit like the savvy, precise innings-eater the Red Sox inked to a two-year contract.