Calling the captains top tiers at this time gives a very false perception of the Espada, when captains themselves ranged from Hitsuigaiya to Shunsui to genuine top tiers at the time like Unohana—who Aizen deliberately didn’t want to fight.
Ichigo was training his mask regardless of Grimmjkw because he couldn’t use bankai without the threat of the hollow overtaking him. The second he has control he scars Grimmjow and makes Grimmjow hyper focus on him lol.
He gets good scenes on a very weak Ichigo and then pushes a stronger Ichigo to high diff, before Ichigo gets even stronger for his Ulquiorra fight.
Hes not very relevant to the audience afterwards either. Hes just another villain whose only lingering importance is pushing Ichigo to have self doubt in his hollow form again—which only came about because Ichigo as hurting his friends
Again, Espada cannot be the TobiRoppo/All Stars when the MC had his biggest longest fueds and battles with them. If you were talking about WCI then yes it would be a more apt comparison, by the time Wano rolled around tobi roppo and All Stars were far less relevant by default since they were in the rearview for the MC.