I think somehow the difference between his first hit of the 80s (In The Air Tonight) and his last (Another Day In Paradise) encapsulates everything about how (pop) music declined during the decade. The latter even tries to repeat the moody intro of the former, quite pointlessly.
Of course, his 90s stuff (bar the Both Sides album, which essentially was his transparent version of the Blue Nile) was even worse.
As for Alf, I guess (as we discussed before in the 80s Singles thread) some of the sales momentum came from the subsequent non-album hit in spring 1985, That Ole Devil Called Love. And the Live Aid no doubt helped too.