Again, I'm going to say that I think Crystal and his filmmakers did a fantastic job shooting Tiger Stadium to make it look like Yankee Stadium.But given two choices - use a LOT of CGI on Tiger Stadium, or a tiny bit of CGI on Yankee Stadium II - then why choose the latter? If they just took Yankee Stadium II, added the frieze, and called it even, obviously that wouldn't look totally authentic, but it would be good enough. And they wouldn't have to digitally recreate the Bronx, either, since it would basically already be there. Of course the Bronx in 1961 would look different than the Bronx in (whatever year 61 was made) but, well, HOW different? For the small amount of time we see it in the film, I doubt it'd be that big of a deal.The renovations of the early 1970s vastly altered the interior of Yankee Stadium. It was easier to redress Tiger Stadium, and add CGI, than it would have been to try and film in Yankee Stadium.
One of the big things they did, because Tigers had moved out at that point, had nothing to do with CGI. They painted the seats in the stands green to match what they had looked like at Yankee Stadium in the 60s. I doubt that Steinbrenner would have allowed Crystal to do that with the real Yankee Stadium.
At some point, you have to accept a willing suspension of disbelief. 61* worked for me. I was convinced by Tiger Stadium's recreation of Yankee.