Don't know if Brace is a disaster, but there is a pattern of players who have been drafted and later on becoming successful players getting on the field consistently in their first year.
Butler, Chung, Vollmer, Edelman last year...
Mankins as a rookie....
Daniel Graham was a hammer his first year but never developed as a big time catching threat...
Branch and Givens as first year players...
Wilfork made an immediate impact...
Mayo was factor in his first season...
On the other hand guys like PK Sam, Chad Jackson, Wheatley, Crable, Woods, Marquise Hill and others have not gotten on the field consistently their first year (and beyond) and have been generally busts.
I call total BS on this:
Givens played 12 games with 9 catches and barely saw the field except in garbage time. He had unreliable hands and spent the entire offseason after his rookie year with a JUGGS machine. He was a non-factor his rookie year
Wilfork was almost a total non factor until halfway through his rookie season
Warren played sparingly until the last month of the season in his rookie year. He made just 4 starts and 19 tackles
Asante Samuel (you remember him?) 1 start and was primarily a backup (not unlike Wilhite or Wheatley was his rookie year before his injury vs the colts)
Meriweather started no games and got very little meaningful playing time until the end of his rookie season
Graham only started 6 of 12 games his rookie season and was backing up Fauria most of the season (i.e. a lot of his starts were in 2 TE formations)
The pattern is, unless you're a blue chipper (Seymour, Mankins, Mayo), Belichick works you in slowly. This is especially true on defense, where he prefers to go with a veteran and have the young guy displace the vet by the end of year 1 or by the start of year 2. Koppen is one of the few exceptions, but nearly every other rookie - productive player or bust - has been worked in slowly.
The other case when Belichick will play a rookie early and often is in the case of injury (Vollmer) or total ineffectiveness of the veteran (Eugene Wilson).
Your list of "PK Sam, Chad Jackson, Wheatley, Crable, Woods, Marquise Hill and others have not gotten on the field consistently their first year (and beyond) and have been generally busts." is pretty hilarious considering one of those guys has been on IR for 2 years (Crable), one started on PUP IIRC (Jackson) and Wheatley landed on IR halfway through his rookie year. Putting an undrafted Woods and a 5th rounder like PK Sam in the "bust because they weren't good enough to play significant minutes" category is both ridiculous and unrealistically high expectations to put on a rookie.
Fact is, the Pats have been a very good and mostly talented team for the last 10 years. They have had the luxury of working in guys slowly. It's not a sign of failure for a guy to ride the pine a lot his rookie season. Very few rookies can step in and grasp the Patriots system enough for BB's liking for him to throw them out there. Couple that with his near insistence for having a veteran alternative to every rookie, and you get guys who produce far more in year 2 and 3 than their rookie years.