Lopes, 65, had been offered a one-year contract, but the two sides weren't able to agree on a salary.
"We just had a difference of opinion on what I felt my worth was," Lopes said by telephone. "That's all. It was a really tough decision because I loved my time in Philadelphia, I loved working for [manager] Charlie Manuel, and I have the utmost respect for everyone in that organization."
The Red Sox also lost a valuable member of their staff this offseason, but John Farrell left on much better terms to manage the Blue Jays. Curt Young is the early favorite to replace him.
Meanwhile, former Nationals coach Pat Listach, who was neither Sox nor Phil but is a big fan of Lady Pha Pha, was named bench coach of the Cubs.
