The future of New England Patriots tight end Rob Gronkowski has been the subject of much speculation all offseason. Although, sources tell ESPN’s Jeff Darlington that despite physical and mental fatigue, Gronk is leaning toward returning and is ‘pretty certain’ he’ll be back in 2018 as long as Tom Brady also remains with the team.

But Darlington notes that there is some ongoing friction between Gronk and head coach Bill Belichick that could still affect whether the star tight end is still with the team next season.

Lingering frustrations remain between Gronkowski and head coach Bill Belichick, along with others in the Patriots organization, according to sources close to each side. Whether those frustrations on either side will impact Gronkowski's return to the team remains the final piece to this unfinished puzzle.

Darlington says that Belichick has grown frustrated with Gronkowski since the end of the season and is unsure if he remains “all-in” on the team. Belichick apparently took notice of Gronk’s veiled message of discontent in his farewell message to departing teammate Danny Amendola on Instagram, where he wrote “Be FREE, Be HAPPY (sic).”

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On the bright side, sources close to Gronkowski and Belichick believe that the relationship is not beyond repair and that the friction between the two will subside if Gronk shows his commitment to football.

Although, nothing is completely off the table when Belichick and the Patriots are concerned. Rumors of a possible Gronkowski trade have surfaced in recent days and something could yet materialize in the coming months before the start of the new season.