If I were writing this in early June, what to do about the shortstop position in 2010 would be an easy question to answer - Ryan Theriot was playing very well and keeping him there was an obvious move. But a baseball season is more than two months long and Theriot has slid a little since his fairly hot start, and that leaves questions about what to do with him.

Through the end of may, Theriot had a .293/.355/.459 batting line, which is very good for a shortstop. But since then, he’s hitting only .282/.325/.339. It was nice seeing him hit for a little power while it lasted, but it’s not surprising that he’s not really slugging. What is surprising is that on-base percentage. His season .335 OBP is about 50 points lower than last season’s and about 20 points lower than I would have guessed he’d be able to put up. He’s walking .43 times for every strikeout, his lowest total ever. (Last season he walked 1.26 times for every time he struck out.)

Meanwhile, he’s made up for some of that with his glove. I’m certainly not a scout, but to me he simply looks better as a shortstop this season than last season, and his UZR/150 numbers bear that out. In 2008 his UZR/150 was .7 runs above average per 150 games - basically negligible. This season it’s 5.5 runs, which isn’t amazing, but is obviously good. As a result, even with the slide in hitting this season, Theriot has been worth 2.3 wins above replacement so far this season, not too far off his mark of 3.1 last year.

That’s not to say the Cubs shouldn’t consider doing something with Theriot. For starters, Theriot hasn’t always played shortstop. For a long time, the Cubs were grooming him for second base. If he were to move back over there, his glove would probably be even more valuable than it has been this season. Defensively he’d probably be at least as good as Fontenot, with the difference being that he’s an adequate major-league hitter, too.

The Cubs have a couple of intriguing shortstop prospects in the minors, but none of them is probably ready to start at shortstop just yet (with the possible, but unlikely, exception of Darwin Barney). The Cubs could entertain the idea of signing Orlando Cabrera, who should be a free agent, but he’s been pretty bad this season, both on offense and defense. Miguel Tejada is another free agent, but his numbers suggest that on balance he’s not as good as Theriot at this stage in their careers (although he’s a lot more talented; he can simply do things Theriot can’t sometimes).

The one free agent I find sort of intriguing is Marco Scutaro. I think signing him might be a bad idea - he’s having a career year going into free agency, and he’s probably going to be overpriced. This year he’s hitting for power, he’s walking quite a bit, and he’s fielding about as well as Theriot. The drawback is that he’s 34 and he’s got career numbers that are roughly in line with what you can expect out of Theriot, give or take a little.

But still, the prospect is intriguing for two reasons. First, it’s possible that Scutaro’s career year is in part because he figured something out. His BABIP isn’t crazy, and just from looking at his numbers, he’s simply driving the ball more and taking more walks. But second, even if his numbers were just Theriot-esque, if you put Theriot at second base he’d be a lot more valuable than Fontenot has been. In other words, you wouldn’t be replacing Theriot with Scutaro, you’d be replacing Fontenot with him at a price that’s a lot cheaper than you’d have to pay for Chone Figgins.

I’m not sure the numbers on that work out. For starters, I don’t know what Scutaro is really going to cost in the offseason. I also don’t know how real his 2009 numbers are. And I’m not entirely sure what the value of Theriot at second over Fontenot or a Fontenot/Baker platoon really is, especially because I can’t assess what the value of the extra roster spot you have to devote to a platoon is. I may try to break this down further in the offseason, but for now I’ll say that it’s an idea that the Cubs should at least consider, even if it turns out not to be a great one. I’d be happy going into 2010 with Theriot at shortstop, but if the Cubs can utilize his skills better, they ought to look at whether they have a way to do that.