The A’s officially announced the signing of left-hander Rich Hill on Friday.

To clear a spot on the 40-man roster, they designated pitcher A.J. Griffin for assignment.

Hill received a one-year $6 million deal, and he’s expected to slide right into the A’s five-man rotation, though he’s primarily been a reliever for the past several years outside of four impressive starts for Boston last September.

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Hill is expected to be made available to the media Friday afternoon.

Griffin has missed the past two seasons while recovering from Tommy John surgery as well as shoulder issues that also surfaced in 2015. The A’s have 10 days to trade, release or send Griffin to the minors if he were to clear waivers. The 27-year-old right-hander went 21-11 with a 3.60 ERA in 47 starts with Oakland spanning 2012-13.

He’s been viewed as possible insurance for the A’s rotation were he to make a full recovery, with fellow right-hander Jarrod Parker – battling back from elbow injuries that have sidelined him the past two seasons – in a similar boat.