He was grousing all season, he was having Meyers benched, he was demanding they acquire vets like AB and Sanu... I doubt entirely he tried less.
He knows how hard it is to win a ring, he was leaving anyway, he knew it and said so a year later on Howard Stern. He was dealing with multiple injuries... his injured O-Line got him beaten up earlier in the season. The offense got worse and worse in 2019 and one can track how they got worse in lockstep with injuries he acquired. Ring or no ring he was leaving, he'd rather have the ring and be gone than not. They just weren't good enough at the end of the season to win.