I don't get the trade for Miller

I mean he WAS a great player. But a second and third for one year and the money to cover it just seems like a lot for a rental player who has seen three years pass since his last great year.
He may be awesome but we have other needs like PR/KR, a fifth WR, a third corner, an ILB and even a third RB.
I think Miller will thrive with Donald and Floyd I just see needs elsewhere and that's a lot to pay for eight games.