By Alek Arend Rob Gronkowski thinks one of the top Super Bowl contenders in the NFL is a “mentally soft” football team. The Dallas Cowboys had a couple of good weeks come to an abrupt end with a 31-10 loss to the Buffalo Bills on Sunday. They’re still locked in the NFC Playoff picture, but there are real concerns about how far the historic NFL franchise can go, especially when matched up against the NFC’s toughest teams. After the Cowboys’ loss to the Bills, Gronkowski called Mike McCarthy’s squad a “mentally soft” football team. That’s significant, especially considering Gronkowski was a memb…