With the trading deadline 30 days away, it’s hard to imagine the Red Sox making a blockbuster deal. After an offseason in which they avoided big-name signings and major roster shake-ups, they have compiled the best record in the American League and a decent lead in their division. There is no reason to think they will change course now and risk wrecking a good thing. They can, however, plug holes on a team that on Sunday manager John Farrell reminded everyone is not perfect. The rotation and bullpen each need a boost, plus the left side of the infield is thin. Here, then, is a primer on questions the Red Sox are asking themselves as they also begin asking other teams what they have to offer. Does the rotation need an ace or just a good starter? There is a long list of starting pitchers who are rumored to be available — Marlins right-hander Ricky Nolasco, Cubs right-hander Scott Feldman, Astros right-hander Bud Norris, Brewers right-hander Yovani Gallardo, White Sox right-hander Jake Peavy — but two deserve special attention: Phillies left-hander Cliff Lee and Cubs right-hander Matt Garza. Lee is by far the best starter in the group, but he has $75 million left on a deal guaranteed through 2015. Acquiring Lee runs counter to the Red Sox’ most recent spending philosophy, but if they were willing to take on the bulk of that contract, Philadelphia’s demand in prospects returned might be low enough for the Sox to take a long look at such a deal. He’s the one difference-maker. Garza always has intrigued the Sox, plus he’s a free agent after this season. As an ex-Ray, the Sox know very well he can pitch in this division. He will come at a high prospect cost, and Cubs president Theo Epstein knows the Red Sox farm system well. Cubs general manager Jed Hoyer knows the Padres system well, too, and there are rumors San Diego is a better fit.