Can Red Sox build on stellar opening half?

The key to second-half improvement for a Red Sox team that finished the first half with the American League’s best record is building upon what they’ve already established.

The Sox have the second-best overall pitching staff in ERA and led the AL with a bullpen ERA of 3.42 over the season’s first 82 games — so there’s very little need for tinkering in either department.

Boston has so much pitching depth, in fact, that there could be surplus rotation or bullpen arms available in a trade.

The Sox must hope that David Ortiz stays healthy and continues to slug as he has in the last six weeks, and that 35-year-old Mike Lowell can again be a steady contributor in the second half despite his surgically repaired right hip.

If the Sox can keep Lowell healthy and integrate shortstop Jed Lowrie into the lineup following left wrist surgery, there may not be a need to go outside the organization for the team’s needs.

But if Lowell can’t stay healthy, then look for the Sox to deal some surplus arms for corner infield help like Colorado’s Garret Atkins, Kansas City’s Mark Teahan or Washington’s Nick Johnson.