A kangaroo would kill/maim you if you went close enough to touch it. They are vicious, powerful animals. About the only thing we have that won't kill you are trees. Oh wait... http://www.bio.davidson.edu/people/kabernd/seminar/2001/home/mad/nettles/Dendrocnide/dendrocnide.html
Again, Sloth, we can only tell his worth by going off what we know. As Manpe said up the page, keeping the ball is the most important thing. By analysing his interceptions (which unlike assists can't be helped by something- it will all be Mikel's own work) and tackles you can know just how good or bad he is.
Your proof is entirely subjective. Come up with proper, hard, sports science evidence, like distance covered, successful challenges per season, interceptions, wattage output, etc. You still haven't qualified your argument.