From the argument in Lafler (I guess it will eventually be Cooper, who is the habeas petitioner - not gonna make that mistake again), I get the sense that the judges are willing to conclude that a defendant can advance an IAC claim based on an attorney's deficient performance during plea negotiations, even if the defendant subsequently was convicted after trial.
The appropriate remedy is what the Court seemed to struggle over more. In the district courts in New York, we have seen a lot of specific performance of the plea offer. That is the easiest remedy to identify and apply, but is it the most equitable one? I don't think most of the Judges feel that it was. Another problem with the specific situation in Cooper is that both Breyer and Sotomayor seemed to think that counsel's conduct may not have been deficient, even though the State conceded that it had been.
When I get a chance to read Frye, I'll update this post with additional thoughts.