The alternatives to Pedro were Wakefield, Ramiro Mendoza, Mike Myers, and Curtis Leskanic. Arroyo had pitched an inning in Game 6. Foulke was on fumes as it was.
I have to believe Wake was the "break glass in case" pitcher. Myers was used strictly as a LOOGY. Leskanic left his arm at Fenway. Mendoza, well, 'nuff sed.
As for the Workman at-bat, Peavy, Doubront, Breslow, and Tazawa were already used. On the bench were David Ross, Mike Napoli and Quintin Berry.
A tie game on the road should have been the opening to start Koji in the 9th. Seems to me that Farrell fell into the same trap that a lot of managers fell into at that point in time and attempted to save the relief ace for extra innings. Even the overrated Joe Maddon has been known to do that. Also, 1 out with the bases empty is not a huge scoring opportunity. And there was no platoon advantage to using Ross or Napoli in that situation. Using Napoli means that there's no chance for a defensive replacement for Ortiz later unless you want to put the pitcher's spot batting 3rd in the 10th inning. Using Ross does also limit some flexibility in the catcher position.
I'm not endorsing Farrell's decision; just explaining the context. He did redeem himself in Game 4, using Lackey in a critical late inning situation, and pinch running for Papi in the 7th with a lead. I don't hate Farrell; winning a ring and being a needed change from Bobby Valentine means he shouldn't have to buy a drink in Boston.