Dude, these have a 54% capacity factor. That craps all over land based ones. They can afford to pay for some maintenance. That means on average these turbines were producing 2.7 MW for 5 years. That's freaking huge compared to most land based units.
Each of these turbines has made roughly 140 GWH, or something like $14M each in 5 years. That's a likely to be a pretty decent RoI. If they can refurb these things a few times then they're likely doing pretty well.
The capital cost seem a bit high on these units, but that's likely to be a first mover issue.