Red Sox Pitching Staff Remains in Flux After First Full Month of Regular Season

We’re a full month into the season, but the Red Sox pitching staff remains in flux.

Aaron Cook will make his Red Sox debut on Saturday in place of Josh Beckett. We’ve been talking about Cook (3-0, 1.89 ERA in Pawtucket) for weeks. Now, we’ll see what he can do back in the big leagues.

Clayton Mortensen made his Red Sox debut Wednesday night, striking out six in three innings of work. It was an impressive relief appearance for Mortensen, who was acquired from Colorado this offseason for Marco Scutaro. It will probably be a short stay for the lanky righty as he’ll undoubtedly be headed back to Triple-A in exchange for Cook this weekend.

If he is, he’ll join Daisuke Matsuzaka. Dice-K will be making his third rehab start this weekend with the PawSox. Expectations have quietly been building for Matsuzaka, who appears to be in the best shape of his MLB career and will eventually pitch for a manager who understands the Japanese pitching psyche.

Another rehabbing pitcher in Pawtucket is Andrew Miller, who is nearing the end of his rehab stint.  The 30-day clock runs out on Monday, meaning the Sox will either have to call him up or put him through waivers.

The Sox already have two lefties in the bullpen. Rich Hill rejoined the team last week, fewer than 11 months after Tommy John surgery. It will be interesting to see where, and if, Miller fits into the staff.

Ben Cherington and Bobby Valentine have plenty of decisions to make. They already navigated the tricky process of getting Cook on the roster and into the starting rotation.  Now they need to figure out what to do with Miller, Matsuzaka and even Mortensen. 

Having too many pitchers is a good problem. Trouble is, the team’s big-league pitching has not been good for most of the year.

After losing two of three to the anemic Oakland A’s, the Sox still have the second-highest ERA in baseball (5.44, nearly 1.5 runs higher than the AL average). The bullpen has improved considerably of late (just two earned runs in the last 28 innings) but still comes in with a 5.35 ERA — the highest in Major League Baseball  and nearly two runs higher than the league average.

The bullpen started to fall into shape during the road trip, in large part because the starters were going deeper into games. With Cook on board, we’ll be watching every pitch thrown by the team’s starters in the coming days, trying to decide who will be the odd man out when Bobby V settles on a five-man rotation. Felix Doubront and Daniel Bard, the two youngsters in the back end of the rotation, didn’t help their respective causes against the A’s.

On Tuesday, Doubront lasted just 4 innings in a 5-3 loss. He threw 30 pitches in the first inning, gave up all five earned runs, and saw his ERA balloon to 5.19. It’s now the second-highest of any starter on the team.

One night later, a four-run sixth inning did Bard in. He never made it out of the inning, giving up five total runs and 5 1/3 innings. His ERA is now 4.38.

Barring an injury to another starter, it’s likely one of those two pitchers will go to the bullpen at the end of the 20-games-in-20-days stretch that begins Friday. In fact, if Matsuzaka is ready to go you might see both of them in the pen. The team is balancing the long-term goal of turning them into young starters with the short-term needs of the 2012 season. Both will need to limit their innings somewhere down the line; sending them back to the pen after two months as starters might not be a bad way to do it.

Point is, the pitching staff you see now is not the staff you’ll see on Memorial Day. For a team that has given up nearly six runs a game this season, that has to be considered a good thing.