Jose Mourinho may be coming back to the English Premier League after less than a season away. According to a report in the Spanish newspaper El Pais, Mourinho has signed a pre-contract with Manchester United. This agreement requires United to pay the former Chelsea manager $21.6 million if the club does not hire him for the 2016-2017 season. Such stringent terms — if the report is correct — should guarantee that current United Manager Louis van Gaal will be replaced by Mourinho at the end of the season.

The Manchester United side that Mourinho will take over is a confounding one. Despite a wage bill among the highest in the league, the Red Devils are likely headed for a finish outside the Champions League places. Those wages have bought only a sixth- and a fourth-place finish in the last two seasons as well. Manchester United surely has the resources to compete regularly at the top of both the Premier League and the Champions League. In the last few years, the Manchester giants have done neither.

This is particularly galling for United fans because they had become used to the team not merely performing at a level that befits its economic power but consistently overachieving those expectations.

The following graphic shows clubs’ Premier League points totals and wage bills, adjusted for inflation. Under Alex Ferguson, Manchester United was dominant in economic and soccer terms. van Gaal and David Moyes were not only unable to replicate his results, but could not even get the club to perform up to the level of its wage bill.

So there is obvious room for improvement. The problem for United is that the team that underperformed its wages is still signed for next year. Ferguson left behind an aging roster in need of overhaul, and United in the last three seasons has depended heavily on new talent acquired not by Ferguson but by front-office man Ed Woodward. It is unlikely that the players Woodward signed were actually fantastic but have underperformed for three years under two different managers, and much more likely that the club has done poorly in the transfer market. It will require a period of rebuilding to get the roster back up to the level in should be.

This is where Mourinho comes in. He is a tactical manager with a history of remaking teams in his own image for immediate success. The problem is, that narrative does not quite fit the facts of his career. In his last three managerial jobs, in his first year Mourinho has only improved the club’s point total by an average of 0.7 points, and each time the team has finished in the same position it did the year before Mourinho arrived. He made an incredible impact at Chelsea in 2004, helping the Blues jump 16 points and walk to the Premier League title. But that season was more than a decade ago, and the evidence of Mourinho’s ability as a turnaround artist is relatively limited.

At the same time, the evidence also belies one of the great criticisms of Mourinho — that he fails to leave a club in better shape than he found it, and clubs collapse after he departs. While this season at Chelsea saw a spectacular collapse, that was a first in Mourinho’s career. His final seasons previously at Chelsea, Inter Milan and Real Madrid were perfectly good. The year after he left Real Madrid was the season of La Decima, the club’s tenth Champions League crown. Two years after Mourinho left Chelsea for the first time, the Blues won the Premier League title again. Even this year at Chelsea, the underlying numbers show that Mourinho had mostly fixed what went wrong early in the season, but he got sacked in the midst of an ill-timed finishing slump.

The supposed risks, then, should not worry Manchester United fans very much. There are no demonstrable negative long-term effects of being managed by Mourinho.  The more pressing problem is that Manchester United has problems that will not be simple to fix, and Mourinho does not have a consistent history of immediately fixing problems after he is hired. In fact, Mourinho has never taken over a top-level club which was this far short of a title, or even outside the Champions League. This will be a new set of problems.

Mourinho is a good manager with a history of building excellent teams, but usually from already-excellent raw materials. The real question at Manchester United is not what Mourinho will leave behind, but how quickly and effectively he can rebuild a struggling club.