Pretty sure it's more of a case of "what we want build" vs "What have you done for me lately" She's really popular in Minn I believe and a giving her time to accomplish things also extending her might help with recruiting?
She also had discipline issues with her star guard (who subsequently quit) and with a couple of seniors who allegedly sided with Pitts the guard. A bunch of posters on the GopherHole didn't like the Whalen hire so have been posting like the guys here on Prohm. Me, I'll give her some time to build some regional recruiting back. Culture and system (play some defense) change needed and will take more than a couple of years. Won't surprise me if one or two of the previous staff recruits transfer after the season.
Think the extension is a little message that the AD is siding with the coach and not the gossip hounds and a few disgruntled players recruited by the ex-coach. Helps spike the negative recruiting e.g. "Hey, Whalen will be gone in a couple years, come play for us instead!"
From Star Trib:
Whalen should have an infusion of talent next season thanks to Syracuse transfer Kadiatou Sissoko and a strong incoming recruiting class. Whalen’s extension carries her through the senior seasons of those incoming freshmen, a standard procedure in major college coaching.