Stephen Strasburg has not yet thrown off a mound in his rehab from Tommy John surgery, which places him slightly behind the schedule Jordan Zimmermann followed one year ago. That does not necessarily portend any problem with Strasburg’s recovery, but it might mean he’s more likely to return next season than this one.

(Jonathan Newton)

Last year, in spring training, Zimmermann threw off a mound for the first time precisely seven months and three days after his surgery. Strasburg’s surgery happened exactly seven months, 10 days ago.

But, as Nationals officials have emphasized ever since Strasburg underwent the surgery, not every pitcher advances at the same rate when rehabbing from ligament-replacement surgery. The recovery takes between 12 and 18 months, and just because Zimmermann’s took about a year does not mean Strasburg’s will, too.

“You’ve got to be really careful what the schedule is,” McCatty said. “You don’t want to rush it. I know that he’s been throwing and there have been no problems.”

In regard to Strasburg returning this season or next, Strasburg having yet to throw off a mound could make a difference, based on Zimmermann’s progression a year ago. Zimmermann made his major league return on Aug. 26, 157 days after he threw off a mound for the first time. In 157 days, it will be Sept. 17 and the Nationals will have only 10 games remaining in the 2011 season.

Again, it can be risky to contrast and compare one pitcher recovering from Tommy John surgery to another. Strasburg shouldn’t be ruled out to return this season. And, anyway, the Nationals have placed the priority only on fully healing Strasburg, not at all on whether it happens this year or next. But given where Strasburg currently is, it seems more likely he returns in 2012 than at the end of this year.