You should respect cards, position, chip stack sizes and other poker factors before trying to give players a rating.
They will quickly expose themselves by bet sizing, position bets, and how often they splash around.
Eventually you will see some showdown cards that will likely validate your findings/feelings.
Occasionally you will discover that someone you thought was weaker than you imagined, was just a "trapper" and has some skills, and likewise, you will find a player you gave "monsters under the bed" status, isn't that good.
The thing you must remember is that smart players vary their play and morph into different characters as the tournament winds on, and they amass chips, so your initial characterization might have been spot on, but if you keep relying on it later in the event, it might not be as accurate (when limits are high, more risk in play, players adjust radically). gl