Highly interpretative stats? They are black and white, easily comparable against others we have in that position and are definitive based on a relatively high sample size. Factor in his age, the years played at certain levels, the interest or lack of from other clubs and the overwhelming observations of those who have watched him week in week out allows one to form an opinion from a variety of sources. Yours just seems to be based on the fact we've signed him so automatically with the rose tinted specs on believe he's the real deal without looking into the bigger picture of him or how he'll fit in or improve us.
It is also possible to determine with a degree of probability if he will be a good player or not for us - it is why clubs have scouting networks and all other manner of stats available to them before they sign players. This signing seems to based on the fact he played well in a dozen games at two leagues below our current one for our current boss who had previously transfer listed him. Hoping for the best can sometimes be interpreted as blind faith, but having it it doesn't automatically disqualify others from being fan who prefer to make judgments using a greater amount of evidence.