While classifying him as some sort of clogger would be unfair given what he has demonstrated over his career, it's worth bearing in mind not every manager can produce incrementally better performances and/or results with superior player-personnel ingredients or greater funds — in some cases, being in charge of upper echelon or technically superb players even can expose the shortcomings of coaches as they can't synthesize the perfect environment for the true difference-makers to excel (while operating within the collective framework).
And curiously enough, while Pochettino's teams are stereotypically rambunctious, willing to press and regimented for the most part, he might be the poster-child for that very good but not top, top category as his schemes and in-game approaches have certain limitations/flaws in comparison with Klopp, Guardiola, Tuchel and the emerging guard spearheaded by Nagelsmann (who coach a more coherent and consistently attractive brand of football while maximizing the technical attributes of the best players and putting clear emphasis on optimized juego de posición models).
A lot of us just don't like the process of hiring Mauricio when you have some of the foremost schemers and innovators of the contemporary period in the same league; to go toe to toe with the best of the best, we need someone who can keep pace and occasionally out-think them from a tactical and conceptual perspective — and Pochettino, for all his qualities (which presumably attract United's board), doesn't appear to be the guy that will help us outperform and overcome City (at least while Guardiola is there), Liverpool and Chelsea on a semi-consistent basis.
Apologies for jumping in, by the way; I don't claim to know better, only wanted to share that opinion.