In February, 1972, Roseboro told
Jet magazine that the Angels had offered him a contract in 1970, but he had gone to the Senators because Bob Short had talked about getting him a coaching position, or possibly succeeding Ted Williams as manager one day. So after a year away, Roseboro did go to Orange County, spending 1972-1974 as the Halos' bullpen coach.
This is clearly a 1972 picture, as the Angels have just sewn on the big "A" on the cap, replacing the lower-case "a" (with the halo hovering, not actually on the "a") design of 1971. After '72, presumably, they ordered new caps.