This is nonsense. Earlier on in his managerial career yes, but what has he done in the last 15 years?
He left Barcelona three points ahead of the relegation zone in his second spell there, won one league title in four years at Alkmaar, then went to Bayern - the biggest and most successful side in Germany - and won one league title there when they were a cut above the rest of the German sides. Does he deserve credit for this? Not much considering how one-sided the German league is. It's akin to Celtic winning the SPL, really. In the following season, he was sacked for failing to incentivise and motivate his side leaving them 3rd/4th in the Bundesliga; that is utterly embarrassing because Bayern have more power and wealth than any other German side by a country mile.
He also got to the 2010 Champions League final in the most fortuitous of circumstances. When they got past Fiorentina, the decisive goal was miles offside, which went in Bayern's favour. In addition to this, Robben bailed (no pun intended) Bayern out of games, where they were lackadaisical, with moments of individual brilliance. Very similar to what Bale did at Tottenham in his last season. Bayern were also very lucky to not get knocked out by 10-man Manchester United in the quarter-finals.
He then joined the Netherlands national team and when you look at how he did in 28 games, he won 17 of those but only lost twice. It's worth noting however that 9 of those 17 wins consisted of him getting wins against the likes of Andorra, Estonia, Romania, Turkey and Hungary in the 2014 WC qualification group; sides which, given the quality of the Netherlands team, they are superior to.
Now he's at United and after having spent over £150m, he's only just started to get the balance of his team right. And even then, this was because injuries had forced his hand.
So, to sum up, in the last 15 years:
- nearly got Barcelona relegated in his second spell
- won 1 league title in 4 years with Alkmaar
- won a one-team race in the Bundesliga then bottled it the following season
- reached a European final in the most flukiest way imaginable
- did fairly well with the national team
- only just started to find the right formula for his Man Utd side as a result of injuries
He is a good manager - yes. But elite? No way.