Reinforcements are coming at third base for the Red Sox. How effective they’ll be when they arrive is anyone’s guess, but John Farrell could certainly use the options. The Red Sox manager said Tuesday that he’s hoping Pablo Sandoval (knee strain) will be ready to begin a minor league rehab assignment in the coming days. Rather than traveling with the team, Sandoval has been in Boston, where’s he’s begun freely taking batting practice. “The swelling’s gone,” Farrell said. “He’s feeling better, swinging the bat. That’s not been restrictive, so we’re getting closer.” Brock Holt should beat Sandoval back to the Red Sox, depending how he feels after continued rehab games in Triple-A Pawtucket. Holt, who stopped his rehab assignment last week when he was experiencing more vertigo symptoms, rejoined Pawtucket after a short break. He started in left field last night and was batting third. “Couple of days at DH, get him into the outfield, move him to the infield from there,” Farrell said. “And we’ve got to get through those steps.” Holt was hitting just .133 with a .449 OPS in six games with the Sox before he went on the 10-day disabled list. He never seemed right at the plate, though, admitting later that he was bogged down by illness as early as the first series he played in Detroit.