Anonymous Gearbox Developer:
Somehow the schedules for Pecan and Borderlands 2 managed to line up and GBX realized that there was no fucking way they could cert and ship two titles at the same time. Additionally, campaign (which was being developed by TimeGate) was extremely far behind, even as Pecan’s Beta deadline got closer and closer. In April or May (can’t remember which), Pecan was supposed to hit beta, but GBX instead came to an agreement with SEGA that they would push the release date back one more time, buying GBX around 9 mos extension.
About 5 of those 9 months went to shipping BL2.
via reddit