The argument I heard on mlb network was that he was only great for 5 years. If they allow him in with that small window of greatness it opens up a lot of players that could meet that low bar.
I do get that argument to an extent. That was my argument against Tony O. He won 2 MVPs and had MVP votes in 7 years and won 6 straight gold gloves. He's arguably the best player of the 80s, though I don't think I wouldn't argue that.