Sam Howell wasn't a failed starter, per se. In fact a rumor surfaced leading up to the Detroit game that it was not Ben Johnson who pulled out of the Washington HC interview last year while the hiring committee was in the air. Johnson wanted Howell to start and use pick #2 on something else. Adam Peters cancelled the meeting and turned the plane around.
At the end of the day, Washington not having the personnel, their coordinators not adjusting to their players' best attributes, and Ron Rivera being mediocre at best at both being a GM and a head coach all hurt Howell. He has the arm strength, but he is shorter than ideal. After a few batted passes, he rarely threw the ball over the middle because he can't see or get the ball over his linemen.
It was a good move by both teams at the time. I would love for Howell to get another chance and I believe he has one more year on his rookie deal...and on short money. OTOH, Geno Smith also has one more year, but Smith evidently posted a "cryptic" message about Pete Carroll, who is being hired in Vegas. Perhaps he's trying to work a trade?