According to Jerry Zgoda (of the Star Tribune) the Wolves will also be adding A.J. Price to the training camp roster. There's also a chance that the Wolves could add another big man. With Hummel, Brown, Jeffers and Price the Wolves now have 18 players under contract.
Zgoda thinks one likely scenario is that the Wolves waive Chris Johnson (does have a guaranteed contract) and they keep either Brown or Price as a third-string guard as well as Jeffers (for defense).
I personally, would like to see the Wolves keep either Brown or Price as a backup guard; waive Chris Johnson; and then sign Robbie Hummel as a versatile forward who can knock down some threes (though I see the appeal to Jeffers and his defense--something the Wolves could also use).
It should be an interesting preseason. Media Day is this coming Monday and then the Wolves head to Mankato for a few days for the start of training camp. Minnesota's first preseason game is about a week-and-a-half away (Oct. 7).