Free agent linebacker Preston Brown has a hint of Patriots envy. Quite frankly, it’s hard to blame him. The NFL’s reigning tackles leader has watched former Bills teammates stampede out of Buffalo and turn into stars with the Patriots. It wasn’t easy to process, but now that Brown has a similar opportunity on the open market, he can’t help but think about the possibility. “It’s a little weird,” Brown said of his ex-teammates thriving for their AFC East rivals. “I’m not going to sit here and lie like, ‘Oh well.’ You’re happy for them, but you’re also like, ‘All right, every time somebody goes to the Patriots, they’re going to the Pro Bowl or the Super Bowl.’ It’s something you feel. A lot of guys left the last year, and it seemed like everybody who left us was going to the playoffs — (Rams wide receivers) Sammy Watkins and Robert Woods, (49ers receiver) Marquise Goodwin. Everybody who left had a good season. It’s definitely something you look at like wow, those guys are having success. But the Patriots, they definitely seem to get the best out of the Buffalo Bills.” Brown, who had 144 tackles last season, fits an obvious offseason need for the Patriots. And Bill Belichick is familiar with the middle linebacker after a pre-draft workout at Louisville in 2014, when Brown was selected in the third round. Now, it’s believed the Patriots are among the teams interested in Brown’s services, and his suitors’ curiosity could pique this week as the league converges upon Indianapolis for the scouting combine. The Bills are trying to keep him, and it’s Brown’s preference to stay if they hit his price. There’s a lot to like about Brown, a locker room leader who never has missed a game in his four-year career and has called plays in the huddle. Given the Patriots’ injury woes last season at inside linebacker, Brown’s stability and durability would be desirable as they work to reinforce their front seven.