Interesting data points on IM volume

First off, this is the most important factor for improvement.  Consistency for a LONG time--not just for an 18 week (or whatever) race training program.

Second, you swam more (and have been building for 3 years) and got out of the water much faster.  People drastically underestimate how big an advantage this is.  It's not just the 12min you saved in the water.  It's the energy saved that you can spend on the bike & run.

Third, Cozumel is a much faster course than CdA.  So, you get off the bike faster and, again, spend less effort there.  So you can also have a better run, all else equal.

I am not at all knocking your (well earned) improvements.  That is great and congrats!  But your attribution is probably largely misplaced.

I think having a huge aerobic base really helps with long course racing.  I can only use myslef as an n=1, but as my volume increased so did my race performances.  I actually wrote a blog post on the same subject:

http://somerandomthursday.blogspot.com/#!/2011/11/dont-make-me-herd-you-look-back.html

I'm not saying that othe facts don't play a role (intensity, race pacing, nutrition) but im my case, volume appears to have been the key.

Your first statement is undoubtedly true.  However, you still appear to be leaving other 'false impressions' for yourself and for others.  Your 'data' is not nearly complete and, on its own, is of limited use in making the conclusion that you are trying to make.

x2.  Your 'huge aerobic base' comes not just from your increased volume this year, but all the training you did before that (which, of course, allowed you to do that huge volume this year). 

People seem to constantly try to 'compartmentalize' their training around a race or a year.  And then they see what was 'different' and assume that led to the changed performance.  It is generally not possible to do that with any degree of certainty, despite the 'feeling' that it must be right.  You (speaking generally to any individual) are not a 'control' group.

I agree that consistency is the key.   Consistency, for me, led to bigger volume.  There would have been no improvement, if I didn't do the work (whether long and slow or short and hard) day in and day out.

Watch who you're calling old there, pops! 

Just to echo the thread, the accumulated training is the key here, not the reduced mileage. The fitness from year 1 helped year 2 and 2 helped 3. One of the reasons people often say that it takes years of training to get to a level to KQ.

Nice race by the way!