Both, the board because they don't tell the manager we need to spend to get some top quality in in order that we can challenge and the manager because he refuses to go out and sign the players we need at the price required.
Clearly the board are happy enough for him not to spend as long as we get top 4 and profits remain intact, but as a manager you should be looking to achieve success, this would require him to take a risk and spend some money and thus accepting that top 4 won't be enough for the board if he does.
Basically he's as much to blame as they are, it the board we'rent content they'd send him packing.