I don't see it as the weakest necessarily. I see it as...the least far along, if that makes sense. Everett has clear talent but he's also a rookie and rookie TEs rarely put up big numbers. I have zero doubt the Rams would have drafted Evan Engram at #37 in April had he slipped. That guy is a rare talent (who the Rams will face in 2 weeks). Last year Hunter Henry was the only rookie TE to catch 20+ passes (36) and in the past three years only 8 rookie TEs total caught 20+.
Both Everett and Higbee have flashed ability and also both probably missed a few they should have come down with. Together they've caught 21 of 40 passes thrown their way (52%) and I'd like to see that more like 65%. Though those 21 catches have gone for 333 yards.