Nieves was a popular figure in the clubhouse and a well-liked receiver among the pitching staff, but he struggled offensively this season, batting just .164 in 26 games.
Yankees manager Joe Torre said that the team had several opportunities to change backup catchers over the last month and a half, but did not find an enticing option until the Angels agreed to accept right-handed reliever Jeff Kennard in exchange for Molina.
"We just didn't feel that any of those [options] would give us that big of an upgrade to replace Wil," Torre said. "But with Jose Molina, it's someone who has been a regular player and a regular catcher."
Molina, 32, was batting .224 with 10 RBIs in 40 games for the Angels this season. He was informed of the trade after the Angels' game against the Twins on Saturday and arrived in New York in time for Sunday's game, taking not only Nieves' spot on the roster but also his No. 26.
Molina should see his first action for the Yankees sometime in the Kansas City series. Until then, Torre said he would work in the bullpen warming up pitchers to get an idea for their repertoires and preferences.
"He's a good catcher, so it shouldn't be a problem for him," Torre said.
Molina arrived at Yankee Stadium in the third inning of Sunday's 21-4 rout and said he enjoyed watching his first game from the bench. He also said he looked forward to working with Posada, with whom he played winter ball in Puerto Rico.
"I know he's a veteran guy," Molina said. "I can learn a lot from him."
As for Nieves, the Yankees now have 10 days to make a roster move, exposing him to waivers. Nieves said that he has been in contact with his agent, Mike Nicotera, and said he was hopeful that other organizations liked what he did for the Yankees.
"I'd rather go somewhere else, obviously, and be in the big leagues than go back to Triple-A," Nieves said. "Any baseball player's dream is to be up here. Definitely, I'd rather be somewhere else in the big leagues than go back."
If nothing else, at least Nieves left with a bang. His offensive struggles seemed to be dissipating after he went 2-for-3 with two RBIs in the Yankees' 17-5 victory over the Rays in the second game of Saturday's doubleheader.
"I left here on a good note, a good game," Nieves said. "If you're going to leave, leave with style."
Working him in: One of Nieves' primary tasks had been receiving right-hander Mike Mussina, who lowered his ERA from 6.52 to 4.61 while working exclusively with Nieves.
But Torre said that both Jorge Posada and Mussina had individually broached the idea of resuming their workload together, which began on Friday in a start against the Rays. Torre said that he was happy to see that and expects to team the two together.
Take what they give: On paper, Johnny Damon's offensive output looked pretty good in the Yankees' 17-5 victory -- Damon went 2-for-5 with three runs scored, two doubles and four RBIs in the nightcap, helping him log his fourth and fifth hits in his last 32 at-bats.
But Damon -- who rested for Sunday's series finale -- still doesn't believe he has broken out of the skid that ails him. He critically pointed out that had Carl Crawford been playing left field instead of Jonny Gomes, at least one of his hits would have instead landed in a Tampa Bay glove.
"The bat's still not there," Damon said. "You hope they can [help break out], and I'm happy I got some extra-base hits and drove in some runs. I'm just going to keep going down to the cages and hopefully help the team in K.C."
Henn (in the) house: The Yankees added a fresh arm to their bullpen before Sunday's game, recalling left-hander Sean Henn from Triple-A Scranton/Wilkes-Barre after shipping right-hander Matt DeSalvo back to the farm.
Henn, 27, was 2-0 with a 4.66 ERA in 17 appearances for the Yankees earlier this season, and had gone 1-2 with a 3.00 ERA in 12 games at Scranton/Wilkes-Barre.
Torre said he spoke with general manager Brian Cashman between games of Saturday's twin bill and asked for another arm, with the Yankees expecting to carry Henn -- and thus, 13 pitchers -- at least into the series at Kansas City.
Henn said that his Scranton/Wilkes-Barre teammates have been keeping a close eye on recent callup Shelley Duncan, and they haven't been surprised. Duncan hit his first home run Saturday and was the Yankees' DH again on Sunday.
"They took our best player," Henn said. "He doesn't get cheated when he swings, you've seen that much."
Rookie ball: Duncan is the eighth player to make his Major League debut with the Yankees this season. This is the first time the Yankees have had eight different rookies break in prior to Aug. 1 since 1944, when they had 11, according to the Elias Sports Bureau. The Oakland A's are the only other team in the Majors to have as many as eight players debut so far in 2007.
Coming up: The Yankees take their show on the road for a four-game series at Kansas City opening on Monday, with right-hander Roger Clemens (2-4, 3.88 ERA) taking the mound for New York. Left-hander Odalis Perez (5-8, 5.84 ERA) counters for the Royals, with first pitch set for 8:10 p.m. ET on the YES Network.