DETROIT — Rob Gronkowski left no doubt. Speaking after the Patriots’ 26-10 loss at Detroit on Sunday night, Gronkowski confirmed ESPN’s report that he threatened retirement to stop a trade to the Lions in April. “Yeah. It happened,” Gronkowski before a throng of reporters crowding his locker. “[Tom] Brady’s my quarterback. That’s all. Wasn’t going anywhere without Brady.” According to ESPN’s Adam Schefter, New England and Detroit were in “deep” trade discussions during the week of the draft that. Upon learning he could get dealt, Gronkowski declared his intentions to the Patriots and refused to return the Lions’ calls. Eventually, Gronkowski and New England officials met and began a dialogue that ended outside trade talks and eventually led to $4.3 million in incentives being added to his contract this summer. Through three games, Gronkowski has 13 receptions for 189 yards and a touchdown.