Almost perfect illusion.....
I think most people are amazed at the resemblance between Barry Pepper and Roger Maris, but Thomas Jane really captured the essence of Mantle in all respects - including is speech and mannerisms. I grew up watching the M&M boys, so it was fascinating to me to see how accurately they copied the stances and swings of the original "Bash Brothers".
BUT - the illusion was destroyed for me early on when the two are standing at home plate with Babe Ruth's widow, who is about the same height as (supposedly) 5'11" Mantle & 6' Maris. After that, I was keenly aware of the fact that both actors (especially Barry Pepper) were way, way shorter than the men they portrayed.