The Giants have placed Zito on the DL (15-day variety) for the first time in his career with an extremely vague and mysterious “mid-foot sprain.” Which is a term that somehow manages to sound even more awkward than it looked when it happened.

I shudder to think how badly Zito would have hurt himself were he not protected by the generous cushion of his mustache, which surely prevented greater injury through its Phiten titanium necklace-like effects on Zito’s balance and coordination.

Too bad it couldn’t help his velocity.

Zito injured his foot attempting to field a Joe Saunders bunt in the second inning Saturday against the Diamondbacks. It’s good to know that Saunders’ ownage of the Giants extends further than lazy sliders on the outside corner.

In a way, it is fortunate that Zito will miss a start or two. This injury is really just a much more brief (though arguably less painful) path out of the starting rotation than the one he was already on. But the timing of the injury, and the Giants reaction to it, reveals one of the team’s greatest weaknesses: the back end of the rotation.

Even before the injury, Zito was playing like a wounded man. Jon Miller reported that Zito’s fastball was cruising at a leisurely 82 MPH in the first inning of last night’s game. In a related story, he was also 0-2 with a gaudy 6.23 ERA in three starts this season.

At least now the Giants can finally start reaping the benefits of the one who got away (then went overseas, then was out of baseball)—a former top prospect who was regrettably traded for some guy named Schmidt who was never heard from again.

Returning to San Francisco like the prodigal son of subpar outings is Ryan Vogelsong, who comes back to the Giants from Pittburgh by way of Hyogo, Japan and Anaheim, California. Nothing will be expected of him, aside from not subjecting fans to Guillermo-Mota-as-de-facto-fifth-starter syndrome. Vogelsong’s last full season in the majors was 2004, a season in which he posted a 6.50 ERA, a 1.617 WHIP and went 6-13 in 31 games.

Looking at those numbers, it seems possible that the Giants won’t lose anything in the switch from Zito to Vogelsong.

Realistically, Zito’s starts are always expected to be short and, more often than not, bitter. The orange and black shoes waiting to be filled by Vogelsong are very small in this regard.

The real effect of Zito’s injury—as well as the ineffectiveness of San Francisco’s fourth and fifth starters in 2011—will be measured by the bullpen.

San Francisco’s relievers have been spectacular this season. Last night’s 7.1 IP, 1 ER effort by Mota, Jeremy Affeldt, Sergio Romo and Brian Wilson was reminiscent of team’s run through the postseason in 2010.

But to expect this group to long-relief-by-committee their way through every fifth start this season is unrealistic. And with Madison Bumgarner exhibiting many of the growing pains he somehow managed to avoid last year, there is more pressure than ever on the Giants bullpen.

If Vogelsong can barely keep his head above water, and perform even slightly better than the minimum level of production required for MLB rosterization (AKA Oliver Perez-ing it), he would give the Giants pitching staff a huge boost. If he cannot, well, we’re pretty much back to where we were with Zito.

While things could certainly be worse, this is still not a great place to be.

On the bright side, the Panda is back, baby! And back with a vengeance!

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