But if a week ago you were 1st prestige with 3 1/2 days play time, and now you are 10th prestige with 4 days play time it will be very easy for IW to spot.
It really wouldn't be that hard for IW to catch everyone who has modified their rank and/or leaderboard stats.
If they compared the current leaderboards with those from a week or two ago they could easily pick up any anomalies and request suspensions and issue resets.