Drake fits a lot, seen how he's one of the few characters hinted to actually know about Vegapunks and his research/creations.
He was also mentioned to be MIA by his own subordinates right at the start of the Arc.
The only problem is that Drake doesn't have the skill and strenght to hold his ground against Lucci, Kaku & Stussy... while the man at the Den Den Mushi was pretty confident about it.
Now, if it's Drake AND Smoker (both missing at the G-14 Base) they might have the ability to buy time for Vegapunk in a 2v3...