Lovenkrands did have poor games in the Championship but so did Carroll, he was by and large shite up until about late December (the WBA cup game and Cardiff Friday night game being the turning points). It's poor criteria to base everything on, really.
I'd group Routledge along with Lovenkrands and Guthrie that he's useful against the bottom 6 or 7 sides but other than that he'll struggle in the majority of games at Premier League level. I say majority because Ronaldo will say he did well against A.Cole, which he did tbf.