I don't know how you could argue that Deal is not a good bassist unless you want to go by skill, and you don't come off to me as someone who really gives a sh*t about skill.
Deal makes simple but memorable basslines and you really couldn't have The Pixies without them, they're the foundation for a lot of their songs, they often provide the real drive or hooks to their songs.
But not even the best headphones in the world is gonna do you any good in spotting the bass in You're Living All Over Me or Bug, Barlow was a throwaway bassist during his tenure with Dino Jr, plain and simple. They clearly did alright without him, they had at least two more good albums and holy sh*t those had actual basslines. Hmm...
Bass does play a bigger role in Sebadoh and I can agree that technically he is better, but yeah, Sebadoh being the definition of sh*tty lo fi, technical skill isn't doing him the world of good. Overall I consider him to be a very mediocre songwriter, he wrote the two worst songs from YLAOM, seriously, why is this guy so popular?
Saying a disposable, inaudible bassist for a band that during his tenure didn't emphasize bass at all is somehow better than a bassist who provided the hooks for a band that was all about poppy basslines that were to be copied shamelessly by most alt rock bassists for the next 20 years? Yeah, I think you're being heavly influenced by a little thing called fanboism.