John Lackey-Allen Craig/Joe Kelly trade shows how fast depth can vanish

It’s everything-must-go day in Boston, and the most recent beneficiary is St. Louis, which picked up veteran right-handed starter John Lackey and minor league left-hander Corey Littrell in return for slumping slugger Allen Craig and 26-year-old right-hander Joe Kelly. That last year’s World Series opponents would, just nine months after 2013’s last out, match up in such a deal is evidence of the capriciousness with which the Baseball Gods regard the word “depth.” They like it about as much as they liked disco or a good real-estate bubble -- by the time you can point to it as something that’s happening, it’s already over.

The St. Louis Cardinals entered the 2014 season with all the pitching depth imaginable. Remember, this was a team so rich in pitching that in last year’s playoffs it all but told Shelby Miller to go home, see you at spring training. They opened the campaign with a rotation of Adam Wainwright, Michael Wacha, Lance Lynn, Shelby Miller, and Joe Kelly. They also had hard-throwing righty Carlos Martinez waiting in the wings -- well, more specifically, in the bullpen -- as well as veteran Jaime Garcia, who made his return from labrum and rotator-cuff surgery in May. There was additional support from 2013 first-rounder Marco Gonzales, who was thought to be not far away, and 26-year-old fringe lefty Tyler Lyons.

Wainwright has delivered a Cy Young-worthy performance thus far, or at least one that would qualify in a non-Clayton Kershaw world; Lynn has had the best season of his career. But put them aside, preferably in a safe place, and nothing else has gone as planned.

Miller, who must be Mr. Confidence after last fall’s vote of no confidence, has had a 4.65 ERA from May on -- the average National League starting pitcher has a 3.77 ERA this year -- and increasingly looks like a change-of-scenery candidate this winter if not much sooner. Wacha was brilliant for 15 starts, but has a stress fracture in his shoulder and will be back ... well, we might as well assume he’ll be back eventually. But after being moved to the 60-day DL, Wacha’s now in September-or-go-home territory. Garcia is done for the year surgery to relieve thoracic outlet syndrome and must be considered doubtful ever to be fully healthy again. Martinez has a 4.45 ERA in seven starts, which is better than his 5.00 as a reliever but still not good. Gonzales wasn’t ready. As for Tyler Lyons, he is Tyler Lyons.

Kelly, now Boston’s property, had missed 78 games on the disabled list with a hamstring pull he sustained in April. His ERA in three starts before the injury was 0.59. He’s made four starts since returning and has been thrashed, allowing .317/.374/.537 rates and a 7.32 ERA. When healthy, Kelly is a weird pitcher, a guy with a 95-mph fastball who doesn’t get strikeouts, but does induce a lot of grounders. His current 1.2 ground-ball/fly-ball rate would be top-10 in the NL if he had pitched enough innings to qualify. He’ll be a positive in Fenway Park with that tendency, and there’s also the sense that a fresh set of coaching eyes might be able to make more of his considerable stuff. Even a slight reduction in his average walk rate could pay huge dividends.

John Lackey gives the Cardinals a veteran (35-year-old) arm who has bounced back nicely from his lost beer-and-chicken 2012 season, which was spent on the disabled list while recovering from Tommy John surgery. In 50 starts since returning, he’s posted a 3.55 ERA. That’s not dominant, but Lackey has never really answered to that adjective outside of 2007, the season he led the AL in ERA (3.01; the offense was still turned to pizza-oven levels at that point). Still, he’s consistent, with excellent command and an AL league-average strikeout rate that will tick up in the NL. He’s simultaneously desperately needed depth and something much better than that.

Given that the Brewers went 9-16 in July, with their entire offense dying hard (.228/.279/.371), a deal was just begging to be made. The Cardinals are just one game out of the second wild-card spot as it stands, and the NL Central is up for grabs.

Due to an injury provision in his contract, Lackey is signed to play next season for the league minimum. It is highly unlikely that the Cardinals will let him suffer that humiliation. The remedy might take the form of an extension or a simple raise; to do otherwise would risk a disgruntled pitcher serving as a distraction for a full season. Littrell is a long way from the bigs and looks like a throw-in, but youneverknow. An added benefit for the Cardinals is that they have cleared space to play super-prospect Oscar Taveras every day, something that manager Mike Matheny had vocally resisted in recent days. Now he has no choice.

In picking up Craig, the Red Sox get a versatile -- or, if you’re so inclined, position-less -- player who can play any corner badly but was a career .306/.358/.492 hitter heading into this season. Craig has been utterly lost this year (.237/.291/.346), and pure hitters that don’t hit are the definition of fungible. He had been blocked at first base by Matt Adams, and that put added pressure on him to hit. Obviously, he didn’t. The Red Sox are gambling the just-turned-30-year-old finds his way back from the abyss, because he’s signed through 2017, with a team option for 2018. First baseman Mike Napoli is signed through next season, and David Ortiz is locked up at least that long, so it seems as if Craig is outfield-bound for now.

It’s a big deal, in short, and made both bigger and stranger by the fact that it’s between last year’s World Series teams, two great clubs with incredible depth. The Red Sox are dead for 2014, and though they seem to be gunning for a 2015 comeback, that’s no sure thing with the top of their rotation shorn away. The Cardinals had to rethink their pitching staff just to bid for the postseason. The Baseball Gods laugh at “depth.” The Baseball Gods have a dark sense of humor.