Walker is expected to be back in the lineup tonight when the team takes on the Seattle Mariners.
Rivera had been playing a good amount around the infield and would have seen more playing time at first base after the Lucas Duda trade, but it is unknown when he will be back on the field now.
Rivera has a partial tear of his ulnar collateral ligament, the same ligament that pitchers get repaired when they undergo Tommy John surgery. He hits the DL with a batting average of .290 through 214 at-bats.
It will be interesting to see the way manager Terry Collins positions his infielders now that Walker is back.