If you think adding a new glad to a group of loosers will add to their points you do not understand your own ranking system very well. What will happen now is that all other better factions will have a new punching ball, who they most certainly will have a 90% w/l against, which in turn will boost their ranking, and the few points the new glad himself will get will be nothing in comparison. If you put that new glad on the winning team, it actually would make sense.
Actually that is not the case, however, I understand how one might come to that conclusion. The points added to last place team with the addition of the gladiator will usually be greater than the points lost by the top ranked team. It is variable because it depends on the new gladiator being added. Some do well right from the start, some don't.

Good luck in the pit!

-Nate-