Paul,
I of all people would agree with you, because we were on a 3 capping alliance (that won UCF). But we did find that switching into defense mode about 30 seconds before the match was up became critical.
We had one match (during seeding) against 3 of the best cappers at UCF (pink, 1402 and heatwave). We were allied with 1694 a box bot with no arm (and 15" tall) and the other team was 1649, a great rookie capper. We won this match! 1694 played great defense and held down 312 and pink. While 1649 capped away in our backfield. We put up a few and switched to defense and pulled out a close win. This strategy is valid and can win against 3 great cappers.
After seeing this play out a few times, I don't think an all offensive team can beat an effective mixture.
Here's a video