Modern football is governed by computerised stats nowadays, doesn't mean there aren't other glaring obvious things.
Third goal Wolves scored against us for example, you can read stats and compare this and that, here's a simple fact. Had someone lead the defensive line and stopped Winks from breaking it and play the Wolves player onside, there would have been no goal.
Would it be possible that the reason Grilitsch makes more interceptions that he is playing in a team that has less possession than their opponents?
Hoffenheim tend to have more possession than the majority of teams they play. Only 5 teams in the Bundesliga tend to have more possession in a match than them. Dortmund, who are top of the league. Bayern Munich, who are the best team in the country. RB Leipzig and Gladbach (who make up the rest of the top four) and Leverkusen.
I've questioned stats like that in the past, just like you have. If someone makes more tackles it could simply be because positionally they're not as good for example. But that's all I can really go off when giving someone a view of whether or not he'd be worth signing.
£18,000,000 is nothing in my opinion and if the reports are true that we've been scouting him and we sign him, then brilliant. I personally don't think we'll sign anyone this window.
Grillitsch wouldn't even be in my top 5 list of central midfield signings but as his name come up, I was providing stats in his favour. It's usually better than a compilation video (Though i do prefer the individual performance videos that show every touch or tackle as you can get a good idea of his decision making and positional sense in thsoe).