But that is precisely, again, why people rate Hasenhuttl. It's the same as why Klopp at Dortmund was so revered, as was Simeone at Athelti - they were taking lesser quality teams up against a league's dominant team/teams and winning the title. With managers like Hasenhuttl, obviously Soton aren't going to win a title, but they are getting their teams to perform way above the level I think you'd expect with an 'average' manager. The fact he can make it difficult for teams like Liverpool, United, City etc is because of their style - how else would they be competitive in those games when there is such a financial gulf between the teams?
Klopp at Pool is a good example of coaching ability because think of the reputations of players like Mane, Wijnaldum, Henderson, Salah, even VVD who got better (or maybe more accurately were used better) when they joined Liverpool. They were obviously on another level to this current Soton squad but the basic premise of getting a team to function above its level is the same. Then they had that window of Fabinho, Keita and Alisson and went from chasing City to winning the CL and the PL. This is also the same reason why I think a lot of football fans think Pep is overrated (he's a great manager but not the messiah a lot of people used to claim) because he's consistently had the deepest, most expensive and best team on paper and he's not been as dominant as people would have expected.