But there is nothing hidden about the role of a lifetime .287 hitter on a club trying to deal with the loss of the 23 homers and 85 RBIs provided last season by Rivera.
"Juan will be out for a while, and the need to replenish that offense was critical," manager Mike Scioscia said during a media conference call to announce the signing.
"We've always liked his bat," Stoneman said of Hillenbrand. "When news of Rivera's injury came, with the likelihood that it will extend into the season, it provided extra impetus to get after another bat."
Hillenbrand, 31, packs a good one. During a 2006 season which he split between Toronto and San Francisco, and one which was marred by his celebrated fallout with Blue Jays manager John Gibbons, he batted over .300 for the third time in his six-year career.
Hillenbrand also set a personal high with 21 home runs, and drove in 68 runs while logging extensive playing time at each of the three spots where the Angels have a need: first and third base and DH.
"Right now, we need his bat," Scioscia said, "wherever it is. We'll see where he fits in. His versatility will be big for us. He can be adequate at third base, but I imagine he'll get more at-bats at DH or first base ... especially with Juan being down for a while."
During his breakout 2006 season, Rivera logged significant playing time in all three outfield spots, while also taking occasional turns as the DH. He enhanced his career-high power numbers by also batting .310, but, by all accounts, the 28-year-old suffered a nasty break to his left tibia last Wednesday.
According to sketchy reports obtained by Stoneman, Rivera had hit a ground ball to the right side of the infield and got tangled with the pitcher running over to cover the bag.
"I'm told that his procedure is [Wednesday] and that we really won't know [the prognosis] until the mending process has begun," Stoneman said. "So there won't be anything definitive for a while.
"But we just landed a guy who can hit the ball pretty good."
Along with his offense, Hillenbrand packs a little extra baggage. He grumbled about playing time during his final weeks in Toronto, which wasted no time dealing him to San Francisco following his clash with Gibbons.
Stoneman recalled having "some conversations with people" in the immediate wake of that well-publicized incident, but saw no need for additional probing before signing Hillenbrand.
"It's one of those things you put in the past," Stoneman said. It was an incident, it happened, it's gone. It's a new season for everybody."
Added Scioscia, "I know about the incident, and I know it wasn't pleasant. But it's a new start for Shea. He'll fit nicely into our system.
"The way he can swing the bat, his history of being really productive early in the season can be an aspect of us getting off to a better start. Last season, we were swimming upstream right away."
The Angels staggered through a 12-13 April last season, and entered the All-Star break two games below .500. Hillenbrand batted .329 last April, and .306 in the first halves of the
last three seasons.