It might be said that Bengie Molina was the key to getting the Texas Rangers and the San Francisco Giants to the 2010 World Series.
For the first half of the season, he was the Giants' starting catcher, providing the same leadership behind the plate and occasional power at the plate that he had contributed during three previous seasons with San Francisco.
But in late May, the Giants summoned Buster Posey, their top prospect, whose very arrival seemed to suggest the end of Molina's time with the team - or at least his role as their No 1 catcher.
Sure enough, on July 1, the Giants sent Molina off to the Rangers and installed Posey, who had played mostly at first base, behind the plate.
The Rangers, who already led the American League West comfortably, cruised to the division title as Molina stepped into their clubhouse and line-up.
Meanwhile, Posey, belying his inexperience, took charge of the talented Giants' pitching staff and became their clean-up hitter over the second half of the season, helping them overtake the San Diego Padres in the final week to win the National League West.
Truly, the deal that sent Molina to Texas was the kind of trade that helped both teams.
Both clubs made other second- half pick-ups. The Rangers added Cliff Lee, the most sought-after pitcher at the deadline, then later picked up the veterans Jeff Francouer and Jorge Cantu.
The Giants, seeking low-cost help, claimed Cody Ross on waivers and obtained Javier Lopez, a left-handed reliever, at the July 31 deadline, improving their outfield depth and bullpen versatility.
Still, the catchers loomed large, and that continued right into the post-season.
Molina hit a key three-run home run in Game 4 of the AL Championship Series, and also slowed down New York's speedy Brett Gardner on the basepaths.
Posey enjoyed a three-hit game and chipped in with a game-winning RBI in the NL Championship Series, never appearing rattled as a 23-year-old with just four months of big league experience.
"He's been our most clutch hitter," Brian Sabean, the San Francisco general manager, said.
Molina has previous World Series experience with the Angels, and helped defeat the Giants in 2002, San Francisco's last appearance in the Fall Classic.
His post-season play has earned him a newfound respect and at the start of the series, Molina could not hide his enthusiasm.
"Pretty good for a fat kid who people make fun of when he runs," he said.
And there is this: in a sense, Molina cannot lose in this Series.
Thanks to baseball tradition in which veteran players who do not finish the season are still honoured, Molina will get a World Series ring no matter who wins.