I see a bunch of problems in it, but it could be the surface to be fair (haven't looked at many signatures on gloves). I honestly think it's a poor forgery, but I could be wrong.
No problem, just a heads up- besides the ink pooling, bad M's, and sizing issues with the signature, the best detail to look for is placement. Mantle was the best at placing autographs perfectly. You can see that whoever signed this didn't place the autograph in the "best" possible spot- which Mantle always did.