This statement doesn't mean much. Pretty much everyone who watched Asif thinks he is top of the tree (or close to) in skills if we exclude pace.I have watched few ball to ball coverages where he played. No where close to skilled as Bumrah. Even guys like Asif are way more skilled than Bishop.
That doesn't say he wasn't effective. Neither I woukd say Bumrah is better bowler than Bishop. But he had very few modes of operation. Wasim and Bumrah are a delight to watch in the ways they bring in dismissing a batsman.
Just like Wasim was way more skilled than Ambrose, still Ambrose was a better bowler. Bumrah vs Bishop I will wait till Bumrah retires to decide who is better.
Pre injury Bishop had an extra 20kms or so of pace though, and that is a very useful skill to have.