If the Red Sox aren't interested in sacrificing a draft pick for a starting pitcher, or aren't able to secure any of the options fit for the top of the rotation, there's no reason to fret. There are plenty of mid-rotation options available, with the starting pitching market being one of the lone interesting portions of free agent this winter.
The Red Sox don't necessarily need an ace or something akin to one added to their rotation. The problem the last couple of years has been depth more than anything. In 2011, Josh Beckett and Jon Lester combined for a 3.32 ERA in over 400 innings, but the rest of the rotation didn't do so well. Clay Buchholz posted a 3.48 ERA in just 82-2/3 frames before his back caused him to miss the rest of the year. Between his replacements, the historically awful campaign of John Lackey (courtesy of elbow trouble), and the inability of Boston to find a reliable fifth starter, the Red Sox pitching staff as a whole became roughly average despite the excellent nearly 500 innings from Beckett, Buchholz, and Lester.
Just how bad were the others? The other spots in the rotation, manned at different times by seven different starters, combined for a 5.07 ERA in nearly 600 innings of work. That was more than a full run worse than the league-average ERA in 2011. In 2012, Boston didn't have things quite as bad in some ways, but the back-end of the rotation was not strong enough to support down years from Lester, Beckett, and Buchholz, and put up a 5.60 ERA in 442 frames.
Expecting Lester and Buchholz to rebound -- a process that has already begun for Lester, and started for Buchholz all the way back in May -- isn't crazy. But even if they do come back strong, there is still the need for someone reliable in the middle of the rotation to pick up the slack that's been loose for two years now, someone who can give Boston's offense a chance to win consistently. If Buchholz and Lester can pitch well, John Lackey comes back healthy (a more realistic outcome than many want to believe given just how terrible he was in 2011), and Felix Doubront can hold down the fifth spot once more, then there's a base here for something good. But it's not done even if all of that comes to pass: that's where acquiring a pitcher comes in.
Dan Haren: Haren has an option with the Angels for 2013, one valued at $15.5 million with a $3.5 million buyout. Los Angeles wants to re-sign Zack Greinke, though, and because of this, Haren is going to be bought out rather than have his option picked up. This will make Haren a free agent, and someone the Red Sox will be able to acquire, should he be amenable to a move out east.
Haren had his worst full season as a starter in 2012, in part thanks to back problems. This makes him a candidate for a high-money, short-term deal, assuming someone doesn't go all out to get him knowing other clubs might be hesitant. Boston has money to spend, especially on a one- or two-year contract. Over the last three years, he owns a 104 ERA+, but was better than that in two of them -- the two where his back wasn't an issue. He also averaged 217 innings in those three seasons, and Boston could use that, even if Haren is only average. He has the upside to be more, but even something close to his 2010 would help the Sox.
Anibal Sanchez: Sanchez can't be given a qualifying offer, as the Marlins traded him to the Tigers mid-season. That's good news for the Red Sox, who will now have a chance to re-acquire the pitcher they dealt to the then-Florida Marlins over half-a-decade ago. Sanchez has averaged 196 innings per year over the last three, with a 109 ERA+. He struck out nearly three times as many batters as he walked in that stretch, and while he's never hit the 200-inning mark, he's hit at least 31 starts in each of those campaigns.
As a soon-to-be 29-year-old, Sanchez will almost certainly pull in a three- or four-year contract, but for his likely price -- probably somewhere in the $9-to-$12 million range in average annual value -- there's nothing wrong with that. Many Red Sox fans are loathe to spend money on anything but a short-term pillow contract, but sometimes you just need to pay for performance. Sanchez has been consistent, he's been healthy for the last three seasons, and is a candidate to earn every cent of even a four-year, $48 million contract.
Kyle Lohse: Lohse has been great the last two seasons, but for his career, he's been average. There's no reason to believe that, going forward, he's going to be far better than that, his 2012 performance notwithstanding. His walks are at an all-time low, he pitches in a weak division in the National League, and in a park that favors pitchers over hitters by far more than the past performances of Albert Pujols would lead you to believe. There's a risk in taking him out of a park where his career ERA is a full run and change better than his career rate.
It's not that he's a guarantee to be terrible, but he'll likely get paid by someone given his recent performances, and the Red Sox will have other arms to spend money and years on.
Jeremy Guthrie: No, really. Guthrie is a much better pitcher than many people notice, as he's kind of in the Joe Saunders mold of consistently outperforming what his peripherals suggest he should do. The difference is, where Saunders is a guy to bolster the back-end of a rotation, Guthrie can be relied upon in the middle of one. Both, though, are a lesson that after over 1,200 innings in the majors, sometimes ERA is what you need to trust.
Guthrie was awful with the Rockies, but that wasn't a huge surprise. Coors Field isn't a great place for a pitcher who has had issues with the long ball in the past. The jump from Camden -- which increases homers, but not the rest of offense to the degree of Coors -- to Colorado ruined him. But it turned out to be temporary: a return to the tougher AL, as a Kansas City Royal, resulted in the old Guthrie's reemergence. Guthrie posted a 3.16 ERA and 130 ERA+ in 91 innings, striking out three times as many as he walked.
He's averaged over two wins per year in each of the last three, despite the Colorado stint. He's also thrown 200 innings per season in that stretch, with two of those coming in the AL East. Guthrie isn't the sexiest option out there, but he'll be less expensive than most, can likely be had on a shorter term deal, and will produce something the Red Sox haven't been able to for a couple of years: a reliable, league-average hurler to back-up the high-upside options.