Devin Williams spent Thursday night with some of his new pitching coaches with the Mets looking at video of what’s gone wrong for him this season.  “He’s not feeling sorry for himself,” manager Carlos Mendoza said of the closer, who has been scored upon in each of his last four appearances and allowed multiple base runners in six straight outings heading into Friday’s 4-3 loss to the Rockies in which he did not pitch.  “They’re looking for what’s missing here,’’ Mendoza said. “He knows what he needs to do to get out of it. He’ll continue to get opportunities [as closer].”  Williams’ changeup, which helped make him one of the most dominant relievers in the game — at least until Pete Alonso homered off him in the 2024 playoffs — has been hit hard this season, as batters are feasting on it.  President of baseball operations David Stearns said Williams’ “changeup hasn’t been exactly where he wants it yet.”  And his four-seam fastball hasn’t been much more effective.  Pitching coach…