Originally acquired from Atlanta on Aug. 27, 2008, before re-signing with Boston as a free agent on Jan. 15, Kotsay was slowed by injuries to his back and right calf in 2009.
Francona informed Kotsay of the decision on Thursday.
"It wasn't a fun decision or a fun message," Francona said. "This is a guy that came in last year and immediately became a leader in our clubhouse. He's as professional as they get. You learn quickly to admire people like that, and that will certainly never change."
LaRoche, who was not in the Red Sox's starting lineup on Friday, says he's mentally prepared to become a part-time player. Physically? Not so much. The slugger has been a full-time big leaguer since 2005, his second Major League season.
The most likely situation in which LaRoche will crack Boston's lineup is when Youkilis moves across the diamond to spell Lowell, who recently spent time on the disabled list with a strain in his surgically reconstructed right hip.
Just how often that scenario unfolds remains to be seen.
"As a player, it can create some anxiety in the short term," Francona said of inconsistent playing time. "It's my job to communicate. Our goal is not to make people happy. Our goal is to have a clubhouse where guys do the right thing. Our job is to win. When we win, everybody ends up being content.
"There are times when you ask players to put team-oriented goals ahead of personal goals, and I fully expect that will continue to happen. You're talking about guys who show up and usually don't have to look at the lineup card, because they play every day. In the foreseeable future, we're going to have to communicate to guys that that might not necessarily be the case every day. We'll figure it out."
While lacking Kotsay's defensive versatility, LaRoche offers a power bat from the left side of the plate and solid defense at first base. Uncertainty surrounding his playing time is the least of the 29-year-old's worries.
"I haven't even got that far yet," said LaRoche, who has hit at least 20 home runs in each of the past four seasons. "I've talked with Tito a little bit, but we haven't discussed whether it's going to be a platoon situation, or once a week, or never, or every day. I have no idea. I told Tito that I'm pretty easy, and I'm not going to complain much. You tell me when you want me to play, and I'll be out there."
For a player who hasn't been to the postseason since 2005, winning is the bottom line.
"It's going to be different," LaRoche said. "But that's not a bad sacrifice for being on a club that has a chance to go a long way in the playoffs."