These are distinct issues, yet the opinion treats them interchangeably. Here's a typical passage:
"The issue presented to us here is whether a defendant who, prior to January 12, 2005, entered into an otherwise enforceable plea agreement, which included a waiver of right to appeal a sentence, may seek to withdraw his plea based on an alleged mistake as to the mandatory nature of the United States Sentencing Guidelines."
Op. at 5 (emphases added); see also op. at 8 ("Saldana's plea and waiver were also knowing and intelligent."). There's some serious confusion here. First, who cares that there's a plea agreement with an appellate waiver? The law is clear that even enforceable appellate waivers do not bar an appeal claiming that the plea itself is invalid. E.g., United States v. Gomez-Perez, 215 F.3d 315 (2d Cir. 2000). Even Morgan, 406 F.3d 135 (2d Cir. 2005), the case upon which this opinion rests (and no model of clarity itself), recognized this point. Whether a plea agreement or an appellate waiver exists has nothing to do with whether the defendant's plea was knowing and intelligent -- which is apparently the argument raised by the defendant. The defendant's argument (presumably, since the opinion says nothing about it) is that his plea is invalid because, had he been told correctly that the district judge (ex-Judge Martin, no less) would not be bound by the Guidelines range even if he went to trial, and that he could impose a sentence far below that range regardless of whether he pled or was found guilty after trial, he would not have pleaded guilty. Whether a plea agreement or an appellate waiver exists is irrelevant to the determination of this question.
Second, why "alleged" mistake (as to the mandatory nature of the Guidelines)? How's it "alleged" -- surely there's no dispute that when the judge told the defendant that he would be sentenced under mandatory Guidelines, this was a mistake -- given Booker. It wasn't a mistake then, of course, but it surely is one now.
In any event, as a result of this confusion, the opinion relies heavily on Morgan, enforcing an appellate waiver entered into pre-Blakely, to reject Saldana's attempt to vacate his plea. Yet in describing its holding, the opinion speaks not of whether the plea itself is valid, but whether the plea agreement and appellate waiver are enforceable: We "hold that an otherwise valid plea agreement and waiver of right to appeal sentence, entered into before January 12, 2005, is enforceable even if the parties, at the time they entered into the agreement, erroneously believed that the United States Sentencing Guidelines were mandatory rather than advisory." Op. at 12. But this is what Morgan already held -- so what does this opinion add? Oy.