Prime Mosley was a better fighter than Spence so it wouldn't translate to Bud beats Spence therefore Bud beats Shane. Spence had Hell with Porter. The 2000 Mosley would have lit Spence up. Honestly, I don't see Bud hanging with that era of welters. I think Shane, Oscar, Tito, and Ike would all have been too much for him. This crop of welters is weak compared to the 90s/early 00s crop.
Not saying Spence is better than Mosley per se, more that I think Crawford is more skilled than Mosley (albeit maybe not as physically gifted), however I also get that his resume doesn't really stand up at present. He needs a big win to better justify the pick imo.
He's definitely more skilled than Shane. But I really question if he'd be able to cope with Mosley's handspeed and firepower.