Donny van de Beek is enduring a difficult start to his Eintracht Frankfurt career with the Manchester United loanee yet to win over his new fans after leaving the Premier League giants. It certainly wasn’t a good sign, the Dutchman hauled off at half-time during last week’s 1-0 win over relegation-threatened Mainz at the Commerzbank Arena. After displaying a few positive signs during his first two Eintracht Frankfurt outings, this felt like a big step in the wrong direction for Donny van de Beek, farmed out on loan by Manchester United and desperate to jump-start his stalling career in the Bun…