Well Koeman has been managing for 17 years an never won a trophy of note.
He shows way more potential to land a major trophy than Koeman. I doubt Koeman will ever manage in the CL by the way, something that Pochettino has achieved a couple of times.
Every league win as a coach was followed by a season in the CL. He made it to the quarter finals at least twice:
2001: Lost QF with Ajax against AC Milan (in injury time)
2005: with Benfica eliminated Man United, FC Porto, Liverpool, lost to Barcelona in the QF.