People are a bit too hung up on Ten Hag. While I'd have been glad to get him, the fact of the matter is that he hasn't got much of a pedigree. He has only coached for real in the Netherlands, and not for very long, and nobody knows how he might handle a big club because he's never been at one. Not even as a player. We like to fantasize about him being the next Pep/Klopp, but the reality is that we have no idea whatsoever if he would be any kind of success at all. He could just as easily be a disaster. I would welcome giving him the chance to show what he can do, but no one can say that we're definitely missing out on something big. We would be taking a gamble with Ten Hag much moreso than with Poch.
The Dutch league is not exactly a cutthroat competition when you're in charge of Ajax, the club that wins it more often than not. Pochettino took Spurs to the CL final, and while things aren't exactly harmonious for him right now at PSG, that club is notoriously unmanagable. And despite that, they're 11 points clear in Ligue 1 and undefeated thus far in the CL. He'll stroll the league if he stays in France and he led Spurs to their biggest achievement in the modern era. That's infinitely more impressive than winning the Eresdivisie with Ajax.
There are countless managers who impress domestically in smaller leagues but never make it on the big stage. We've only ever seen Ten Hag in the Netherlands as a player and as a first team coach. He has done quite well in Europe by the standards of a club like Ajax, but he hasn't exactly created miracles. He has just done a bit better than you'd expect. We have no notion if he has the competencies to manage a football giant because he has never done it before or even played for a big club.