Solder is at the end of the line. I believe the Patriots need to draft a tackle and let him develop for at least a year. DEs and LB/DEs eat rookies alive in the NFL. No matter how good a rookie left tackle is, he'll need at least a year before he becomes a full-time starter. See: Cannon, Marcus. Cannon looked like a disaster until 2016 when he came into his own physically and had Dante Scarnecchia get the most out of his talents and size.
People are bashing Roberts, but I really like his nose for the ball and his ability to rip through traffic. He's entering his third year in 2018, and paired with guys like Hightower and Van Noy, he brings a big safety skill set to the linebacker position.
On the QB backup role, Bradford is not a full-time starter, but has proven he can step in and deliver quality starts better than Hoyer. Teddy Bridgewater is not going to be in Minnesota this year. That ship sailed with Keenum. Either guy is in a better place behind 41-year-old starter on an elite team that is still the class of the AFC.