When MLB Network was launching in 2009, Bob Costas had a decision to make.

Costas had been with HBO Sports since 2001, hosting his own talk show as well as "Inside the NFL," the network's popular weekly football program. MLB Network wanted the legendary broadcaster to be a part of its team, but HBO demanded cable exclusivity if he was to remain part of that network.

For the lifelong baseball fan, it was an obvious choice.

"For me to leave HBO at that time -- when HBO was the gold standard of almost everything -- just to do baseball and be around baseball, that tells you where my heart was," Costas said. "Baseball was always really important to me."

Fifteen years later, Costas remains an integral part of MLB Network, which will feature the 71-year-old in its newest episode of "The Sounds of Baseball," which debuts Thursday at 8 p.m. ET.

The show, hosted by Matt Vasgersian and Tom Verducci, dives into Costas' celebrated career covering the game, one that stretches back more than four decades.

• Get MLB Network

"Baseball was always tops with me," Costas said. "When I first began learning about sports, baseball was the unquestioned national pastime. I went to my first game at Yankee Stadium with my dad in 1959; [Mickey] Mantle-[Willie] Mays arguments, flipping and trading baseball cards and putting them on a spoke of your bike while you're pedaling around the neighborhood, that was the late '50s, early '60s, being a kid and being a sports fan. The World Series was a bigger deal than the NFL Championship at that time -- and to many of us, it still is.

"I was probably about 11 or 12 when it dawned on me that if I was ever going to get into Yankee Stadium without paying for a ticket, it would be to sit where Mel Allen and Red Barber were sitting, not to stand where Mickey Mantle was standing."

The episode will look back at some of Costas' signature calls such as "The Sandberg Game" in 1984, Derek Jeter's fan-aided home run in the 1996 ALCS, and Stephen Strasburg's electric 2014 debut. Costas' memorable exchange with Tommy Lasorda during the 1988 World Series -- when the Dodgers manager used the broadcaster's assertion that Los Angeles' lineup might have been the weakest in World Series history to help inspire his team -- is also featured.

"What I said was beyond dispute and shouldn't be controversial at all, but Lasorda saw it and told his team, 'See, even Costas doesn't give us a chance,'" Costas said.

Lasorda was named the "Player of the Game" following Game 4, to which the skipper told NBC's Marv Albert, "The MVP should be Bob Costas."

Shortly thereafter, Costas recalls Lasorda telling him, "Bob, thanks. We'll call you when we need you again."

Although Costas has been behind the microphone for so many historic moments, the one he cites as his most memorable came from that same Fall Classic, for which he wasn't even in the booth.

"The one that stands out is one I didn't even call: Game 1 of the 1988 World Series," Costas said. "I was in the Dodgers' dugout when [Kirk] Gibson hit the home run; I was doing pregame and postgame, so I jumped out on the field and interviewed Gibson [after the game]. That was the most dramatic and theatrical baseball moment I have ever been a part of."

After the game, Costas told his producer, David Neal, that they had just witnessed a real-life Roy Hobbs moment, comparing Gibson's heroics to those in the film, "The Natural." Neal took the comparison and ran with it, producing a mashup of the two at-bats that opened the Game 2 broadcast.

Costas' involvement with baseball has extended beyond the broadcast booth on game day, from his work on Ken Burns' "Baseball" documentary to delivering eulogies for both Mickey Mantle and Stan Musial. Costas has also been part of multiple series on MLB Network including "Studio 42 with Bob Costas," "MLB's 20 Greatest Games," "Costas at the Movies" and "The Sounds of Baseball."

"It sounds corny, but I'm just happy to have been a citizen of the game," Costas said. "A lot of stuff that I've done baseball-wise isn't play by play. I have had a kind of varied relationship to the game, but I've always been part of the game."

In 2018, Costas received the Ford C. Frick Award for broadcast excellence by the National Baseball Hall of Fame, affording him one of the most significant honors of his career.

"Outside of family stuff, the single most meaningful thing in my whole life," Costas said. "People might find it strange with all of the other things that I've done, but that whole Cooperstown weekend may have been the highlight of my professional life."