Kjaer is slow and error prone most of the times in last 2 seasons, Burdisso hasnt been so since he left Inter (except reckless tackling at times etc), mainly competent. The difference is Kjaer has an hyped reputation due to his age and earlier promise, while Burdisso is totally condemned still for past fails despite current good/decent performances (Reminds me of Bramble, still judged for Newcastle mistakes despite solid seasons since).
I got that, and said clueless because of how you belittle La Liga and Osvaldo's very good performances there due to that.