Backed by science? He has no record of spending big and it paying off. He also happend to have one of the best strikers in the league come through the academy
. His biggest money signings (might be wrong) Sanchez and Ndombele have been extremely poor.
As above, Sanchez, ndombele, Lo Celso. Heck even sissoko for 30m, lucas 25m. He's bought a lot of trash as well - Wimmer, Janssen, Stambouli. He's lucky levy has been able to get money back for them.
During his 5 years at Spurs, Poch has bought so many quality players at a comparatively cheap price and most important of all, improved them significantly. And, of course, every manager will have their hits and flops, including Klopp and Pep etc. It is basically impossible for any manager to predict which players succeed and which ones fail to adapt. Ndombele and Lo Celso are hardly flops, they are starting to show their quality even under Jose.
Overall, during his tenure, Poch has done a fantastic job at Spurs, provided stability and brought a tumbling Tottenham into recognition and praise, showed steady attacking intent and improvement, developed players, was a pretty good tactician, and despite not winning a trophy came close to the league and UCL. He would be an upgrade over Ole for sure.
In the current scenario, other than Klopp, there is not one single coach in the world who guarantees trophies, not even Pep. I am not a huge fan of Poch but he has shown plenty of potential to be considered as an option for a top club. At this time, our squad needs a good modern coach with very good tactical, attacking acumen and Poch is one of the very few ones, is available now and also has a successful CV in the PL as an added bonus.