I don't know that Kellerman does that. I thought homerism was most prevalent on HBO when Lampley was cheerleading Oscar and Arturo Gatti. I think Max's need to be right is his biggest vice which is really showing itself with his continued diagnosis that Tom Brady is severely diminishing ("falling off the cliff" in his words), a point that he started over two and a half years ago ("Brady is a bum") and continues even after Brady's very recent dissection of his pick in the AFC (Chargers).
My most recent memory of a Max boxing call is Kovalez-Alvarez with Max giving Alvarez more credit than he deserved up until the final round when he concedes Kovalez's power was turning the fight. Shortly after that "Storm" stuns "Krusher" with a windup right to the temple that stuns the boxing world. I did think that he was pro-Canelo in the second GGG fight.
About five weeks ago ESPN signed Kellerman to a multiyear extension that runs through 2025 that includes his current First Take gig, a weekly boxing show, and a "prominent role" in ESPN's boxing coverage where he will preside over the broadcast desk position in the arena, rather than as an infight boxing analyst.