The difference between a shoulder injury and an elbow injury is significant. I picture the elbow as a part of the body that contains ligaments and tendons that connect from point A to point B. The shoulder is more like the world's worst tangled pair of headphones stuck in used chewing gum, and doctors have basically given up trying to untangle them. Pitchers usually come back from elbow injuries. They don't come back from shoulder injuries quite as often.
Then there's stuff like this:
Carpenter was first shut down with what was described as a nerve-related issue in March, when he began feeling weakness and numbness in his arm, shoulder and face following his throwing sessions.
The problem wasn't with the elbow, and it wasn't with the shoulder. It was with thoracic outlet syndrome. Carpenter had to have season-ending surgery, during which he had a rib removed. That led to this creepy screenshot:
Carpenter had the surgery in July, and he was supposed to be out three to six months. Other pitchers have had the procedure done, and some of them never returned. Jeremy Bonderman came back for a season, but Noah Lowry never did. It was reasonable to expect Carpenter miss the rest of the year, at least. Except Carpenter is starting against the Cubs on Friday afternoon, bucking the odds and making a bid for the postseason roster, should the Cardinals hang on to the second Wild Card.
That leads to a couple of questions.
First: How well does Carpenter have to pitch over his first (and final) two starts for the Cardinals to say, oh yeah, we can't go into the playoffs without this guy in the rotation?
Second: Who would get bumped from the rotation to make room for a lighter-by-one-rib Carpenter?
This isn't just about asking which of five pitchers Carpenter would bump. We're talking about a potential playoff series, where four starting pitchers are needed. Adam Wainwright is an obvious choice. He stays. Kyle Lohse is having a fantastic season. He stays.
That leaves two pitchers out of a pile that includes Jaime Garcia, Joe Kelly, Lance Lynn, and Jake Westbrook. Garcia has been stellar in three of his last four starts, and he has playoff experience. Kelly has been okay, with a 4.25 ERA and 38/17 strikeout-to-walk ratio in 48 innings since August. Lynn has been in the bullpen for the later part of the season, but he's recently come back to make two impressive starts. Westbrook is sidelined with an oblique tweak, but he might come back for the playoffs. He is is still Jake Westbrook, though, for better and for worse.
So Carpenter doesn't have to be better than the Cardinals' fourth starter. He has to be better than three of the four other options.
The answer to the first question? Very. Carpenter has to pitch very, very well for the Cardinals to even consider him a viable option. There's a catch, though. He hasn't pitched at all this year. This is his spring training, and he'll be on a pitch count. Considering that, it's hard to see how Carpenter will get enough innings to impress his way into a prominent playoff spot. He'll need to pitch very, very well to get that spot, but he probably won't get the chance.
Garcia's latest surge makes him a good candidate for the third spot. And, without watching Carpenter pitch on Friday, I'd wager that any of the other three options would be preferable to Carpenter. If the playoffs started in November, maybe there would be time. As is, this is more about Carpenter reaching a goal he set for himself, and the Cardinals taking a look so they can plan for next season. If Carpenter looks good, he'll get a spot in the bullpen next month. And if last year was any indication, the Cardinals plan to ride that bullpen again. He could still play a prominent role.
The amazing thing is that Carpenter is pitching at all. Expecting him to start in the seventh game of the NLCS is probably a little much. But that bit up there about the shoulder? Carpenter is one of the greatest success stories in the history of shoulder reconstruction. So while it would be surprising for Carpenter to start for the Cardinals in the playoffs, it wouldn't be that surprising. He's come back from worse.
They just have to make it first.