Waller is a good receiving TE. He's #2 in the NFL among qualifying TEs with 3.32 yards per pass route... which is very impressive.
Waller's breakout happened at 27 years old amidst a WR void for target competition.
The Raiders do not use him in the redzone, which limits his TD upside.
Foster Moreau is clocking in a truly absurd 4.85 yards per pass route as a rookie while being the superior blocker (on a lower sample size, of course).
I don't think this contract is bad at all for the Raiders; however this doesn't mean he's going to be the clear #1 TE in OAK for the next 4 years. Foster Moreau is triggering many of my rookie TE sophomore break out cues; and should not be ignored. There's a very real possibility that they cannibalize each other's production in the coming years (unless OAK opts to not revamp their receiving core-- which seems unlikely given that they've already tried to do that with the AB trade this offseason).