"Did I read it correctly? That he gave up information in return for a lesser sentence, yet still got the maximum?"
Re-read this sentence (see what I did there!) from the article: "Jeremy Hammond, the hacker who cracked open the database of intelligence organization Stratfor, had hoped for some leniency when he pleaded guilty to one charge of violating the Computer Fraud and Abuse Act."
It's more than likely that the leniency part of the plea bargain was in only having to plead to one charge, as opposed to having to defend himself against many more charges.
Additionally, it is the prosecution and defense who plea bargain but no such deals are binding upon the judge so there's still some risk involved for the defendant even after both sides strike a deal. The judge will usually (but by no means always) go by this agreement but is not required to do so.