I can't agree with your conclusion whatsoever. To address the bit in bold, you cannot compare last season with this one when we had players like Lukaku available to us. So if we went on just league games this season then he absolutely would not have done better this season. However, I admit that is a little unfair on Koeman as he had a very tough set of fixtures to start with, so for example the first 5 league games Koeman faced are not comparable to the 5 league games that Unsworth faced.
I judge Koeman on his overall peformance this season though and he won games early on against vastly inferior opposition from poor leagues (3 wins against Ruzomberok and Split, and then one against Sunderland who are about to drop in to League 1). He then admitted in the Atalanta away game that he hadn't prepared the players and we got taken apart by a pretty average side there and then we drew at home to Limassol. In the league he had us 18th conceding 3's and 5's at home to Spurs and Arsenal, and dumped us out of our fairly average Europa League group. We were below standard at home, pathetic away and pathetic in the Europa League with Koeman.
Allardyce has done some things equally as poor as Koeman - the hammerings away against the top sides, struggling away against sides outside the top 6 but he has improved our position overall and been superior to Koeman. Koeman was bailed out against Bournemouth at home by a player he acted disgracefully towards. He got beat at home to Burnley, whereas Allardyce has got us a number of comfortable wins at home - Huddersfield, Swansea, Brighton and Crystal Palace all being wins by 2 clear goals. Allardyce has also got us 2 away wins. Koeman didn't manage a single one in the league from January to October.
And he has also earnt us some points against the better sides - 2 draws against Liverpool and 1 against Chelsea.