It's also going to depend on the race, for a sprint race the run is really going to highlight a bad runner and reward a great runner. Around here a sprint tri will be a sub half mile swim, roughly 10 mile bike ride and a 2-3 mile run. Dropping the bottom 25% of the competitors (there are some people that will do the swim in 20 mins, the bike in an hour and the run in 40 mins, not a good representation of competition, but they are out there doing it), the spread between the swimmers will be about 3-4 minutes, the bikers will be around 5-7 min apart, but the spread on the run can be 8-15 minutes. That's why I'll always be a MOP finisher on the sprints, because I can finish near the front on the swim, and given a bit more training I can probably blaze a top 3 on the bike, but I'll never be able to run a 5 minute mile, maybe at best I could do a 7 or 8 min mile, but there I've already given up 4-6 minutes on a 2 mile course, which I can't get back on such a short bike course.
Now on an IM distance race, things swing a little more back to even. There have been IM's that have been won by a fast bike leg, and some that have been won by a fast run leg.
Andrew