Between seniority numbers 700-799 there are 20 FOs. Odds are that these guys will not want / will not do / have failed a command. So assuming 20% of FOs never achieve command within CX despite having the required seniority, then that reduces the TTC for anyone behind them. In addition, you are assuming that none of the FOs ahead of you will be retiring pre command. There are a lot of 'late joiners' in CX and again this will reduce the TTC for the man who 'hangs in there'. On top of that there are probably a number of Freighter capts in the group and they will not be counted as 'doing a command' in the stats.
Baywatcher ..... stop being a tease!!