Only Alvarez has been decent, and d'Arnaud to a lesser extent (if only his defense would improve.. can't just depend on pitch-framing. Jury's still out on Syndergaard, as he has yet to get out of AAA, and is still blocked by a deep Mets rotation.. when he could be used right to trade for a big bat that the Mets desperately need to contend, if he's not going to reach the majors in New York. And remember, Barreto is a long ways off, Nolin is not really a decent prospect, and Brett Lawrie has never been able to stay healthy in Toronto due to his hard play, which has resulted in various injuries. Graveman is difficult to call. And Nicolino, BTW, is in AA, but is now questionable as a prospect, as his K numbers plunged in 2014..
And Wuilmer Becerra isn't out of rookie ball yet.. he's too far off to project.
And regarding d'Arnaud, he's a great pitch framer, but his defense is Arencibia level bad(2013). It's going to have to improve or Kevin Plawecki will likely steal the starting job by mid-season, and d'Arnaud will likely be moved to the outfield(he does have a decent bat.)