Yeah but how strong really are Luffy and all the guys on his boat?
Jimbei is badass but I think he is the only one off that falling ship that could actively take part in the main parts of this fight. Maybe Ivankov could as well but compared to the 3 admirals, the top division commanders and the big man Whitebeard himself, Luffys crew are small fish in a big pond.
Surely the only way Luffy can get Ace is sneaking to him - but that is so un-Luffy. No doubt Oda has got some major surprises in store…
You're forgetting that Jimbei is a Schichibukai, and is equal to Ace. Ace in turn is in Marco and Jozu's league, so I imagine that Jimbei can hold his own just fine. He fought against a Logia for 5 days straight, so you can't very well say that just because he is with Luffy he is more or less strong than the level we have seen displayed by the Schichis so far. I'd say he is about equal, and thus a force to be reckoned with. And so is Ivankov for that matter, who is an absolute beast. I'd put him at VA level for sure, him and Croc.
Also, one of Jimbei's regular punches is pretty much as powerful as Luffy's Gear Third, so we pretty much know he is a freaking beast. (judging from the Guardian KOs in Impel Down. I would not classify Luffy's group as small fish in a big pond when they bring in a Schichi and an ex-Schichi and a powerful Revolutionary. Luffy I'm not counting because depending on what Oda wants he can have an uber-boost or be an utter weakling, so I'm not gonna count a wildcard such as him.
Finally, what's gonna happen to poor Inazuma? Is he healed yet? I imagine he is somewhat recuperated, otherwise he is screwed.