I'm not entirely sure what you're getting at as without being offensive, it's dodgy english at best.
Are you saying Kroos is brilliant but has been less good under Guardiola's system, or?
Kroos took 84 shots in league and CL, and scored 5 goals, of which he scored 2 in the league in 52 shots. He shoots a lot but doesn't score much for the amount of he shoots. The only reason anyone in England rates him is he managed to score one of his not very many goals a year against England itself, or english teams in the CL and because of his general style... which is bang an incoming ball towards the goal from 25 yards out, he misses loads but when he scores it looks more impressive than your average goal.
He's decent, but 90% of what he does is say the Busquets "just pass it on" role, or 10% shooting of which the majority is poor. He isn't as good as Busquets defensively.
Kroos really hasn't hinted at anything but being a little above average. He would improve the Utd midfield but spending whatever he costs + 150-200k a week he believes he's worth would be better spent on actually great central midfielders or wide players. At 100k a week and a lowish transfer fee he's probably worth a punt but I've never seen a full game in which he's hinted at being one of the best around.