Looking at your power file you burned some serious 20-30 second matches (20 in the first 5 minutes)! Do you/did you train for this? Here's a Hunter Allen prescribed workout that might help...
10 minutes blocks. Each block is 15 seconds ON (150% of FTP)and 15 seconds OFF (50% of FTP) - do up to 3 blocks. You'll be trashed after this workout. I know i am!
Also I'm with MDCatV. Find a strong wheel and stick to it like glue. Make that your race goal and you'll be surprised at how your pack position/finishing position improves.
Last, don't beat yourself up over one race. Everyone has bad days. Like you said you usually ride the back and never get dropped.
gene r