Can't argue with anything you said about Havens, but the Mets have waited a long time for him to get healthy.
He was healthy, for the most part, last year, but struggled in AA. His .215 avg could have been an aberation and he may have a lot of rust due to multiple injuries that caused him to miss alot of development time. The things the Mets probably like are that he's decent defensively, has some pop and despite hitting .215, had a .340 OBP.
Havens is a lot like den Dekker, both are 26 and need to prove they can hit AAA pitching before they can be considered for a ML spot. One way or the other, it'll probably be the last year for both on any prospect top 10 or 20 list.