Warning: Completely rough math and guesstimates ahead.
Today’s announcement that the Tampa Bay Rowdies FC Tampa Bay will play at George Steinbrenner Field in Tampa, the spring home of the New York Yankees, made me wonder if you could actually get a soccer field in there (it’s been done, putting a soccer field in a baseball stadium).
Using Google Maps, Photoshop and some very rudimentary math and eyeball design, here are some mockups of how the field might have to go.
First, a normal-size, 120 yard x 75 yard field. That ain’t gonna fit.

It seems like you can maybe fit a field approximately 109 yards x 66 yards if you move it out a little, tilt it and avoid foul territory. Still, that’s small.

But this article on the St. Pete Times‘ website says, “The field will run across Steinbrenner’s outfield.” That would be amazingly counterproductive, because there aren’t any outfield bleachers there are only outfield seats in right, and the main grandstand would be very far away from the touchline. Even if you brought stands in (which are not cheap), you’re still rendering the bulk of the (good) seats undesirable. You can get more width on this layout, but it’s going to be shorter.

Now, of all the options, Steinbrenner may have been the best from a location and amenities standpoint (other options apparently included the soccer stadiums at the University of Tampa and the University of South Florida). From a field/playing standpoint, it might not have been. I would presume that they checked it out, or somebody told them, “Yeah, we can put a soccer field in there.”
Again, I’m still waiting for actual news coverage of today’s press conference, or an official release. We’ll know more at that point.
EDIT: Okay, here’s the Tampa Tribune story. It says “the playing surface will be stripped across the outfield and over a portion of the infield around first base.” I’m guessing maybe they angle it some more, give up some width to get some length. Obviously, there’s going to be infield dirt on part of it, which doesn’t seem to concern coach Paul Dalglish:
“No concern whatsoever,” Dalglish said. “I think it’s a small price to pay for the standard of the grass that we’ve got. As you can see, it’s absolutely immaculate. There’s no team going to play on better grass this year and that’s for sure.”
I think he’s going to find out that it’s not a small price to pay, regardless of how immaculate the grass is. Rochester played on a baseball field for years, but it’s far from optimal. Hopefully it’s not a long-term thing, and they’ll get their own stadium before too long.
“No concern whatsoever,” Dalglish said. “I think it’s a small price to pay for the standard of the grass that we’ve got. As you can see, it’s absolutely immaculate. There’s no team going to play on better grass this year and that’s for sure.”
Based on the Trib‘s description, the field could be laid out something like this, which is a little longer and wider. Still, you have to have space for benches and for players to take corner kicks, etc.

And you’re still left with the fact that your main grandstand (home plate area) seating is more than 35-40 yards from the near side touchline.
ONE MORE EDIT: And I go through all that, and here’s the rendering from the Rowdies from the actual release. There’s a lot more dirt there. We’ll see how it looks when it’s actually laid out.
Oh, and FC Tampa Bay is still stupid. With “Rowdies,” it’s even moreso.