How much should the St. Louis Cardinals expect from their shortstops in 2013?

Now that it's become apparent that the St. Louis Cardinals really are going into the 2013 season with Ryan Jackson and Pete Kozma, I'm going to have to try a little harder than some people to figure out just what a successful season from them would actually look like.

The problem: I became a baseball fan in a decade when a shortstop could hit .365 and slug .600 across two seasons and be the other other hard-hitting American League shortstop. I'm not sure I'll ever be able to completely adjust to baseball as it exists now, where certain positions are no longer expected to hit like corner outfielders and where we have some idea of just how valuable defense is.

Ryan Jackson and Pete Kozma offer little in the way of offensive upside, except in relation to themselves—Kozma, for instance, gave us the chance to believe he might really be a little better than the worst hitter in the Pacific Coast League. But what does offensive upside look like, for a shortstop?

Like not much at all. Shortstop offense has fallen basically in line with league-wide offense, but it's harder, I think, to make that mental adjustment from .730 to .690 than it is the broader one from .760 to .730; a player with an OPS under .700 used to be so much easier to dismiss. The league average line at shortstop last year—starters and reserves, everybody—was .257/.310/.378. Cardinals shortstops hit .273./.331/.367, thanks mostly to Kozma.

But this is the most sobering slice of the numbers for me: What follows is a list of all the players in Major League Baseball who managed an OPS over .700 while playing at least half the season at shortstop:

That's it. Elliot Johnson, who played 100 games at shortstop for the Tampa Bay Rays, hit .242/.304/.350, added -7 runs on defense, and finished half-a-win over replacement level.

I believe the Cardinals missed an opportunity by failing to upgrade second-and-shortstop in free agency, then, but the bar for replacement shortstops who aren't replacement level is significantly lower than I thought it was. Ryan Jackson can hit well enough to be a bad shortstop; last year's Davenport Translation came out to .249/.304/.353, which exceeds last year's ZIPS projection of .242/.297/.322 enough to be heartening and not so much as to be suspicious.

The question, then, is whether he'll play defense as advertised. Nobody can reasonably expect him to be Brendan Ryan, but if Jackson is just above average he could could find himself somewhere north of adequate. Which isn't bad for an afterthought on last week's top prospect lists.

Of course, he was also an afterthought on last year's bench. The same stipulations apply for Pete Kozma--an OPS over .650, defense somewhere on the right side of average--but if you know what to do with Kozma's career AAA OPS of .610, you're better off than I am.