Yes, that is a bit of hyperbole, but Red Sox pitcher Bob Stanley was durable enough over his career that he was able to start or relieve, and was able to pitch extended innings out of the bullpen. On May 22, 1983 Stanley pitched 10 innings in relief for the Red Sox, which was not that remarkable at the time given his track record. However, no other pitcher in major league baseball has pitched 10 innings in relief since then, so the performance has become memorable in hindsight.
I wrote about it for the SABR Games Project and it is now available online on their website.