Bob Brenly's only curtain call in baseball occurred during a minor league game (teams and date unknown). Brenly's team was on the road, and the home team's fans designated him as the game's "Beer Batter," where if the player struck out, beer in the stadium would be sold at half price for the rest of the inning. Brenly struck out three times that game, and the fans stood on their feet and cheered for him after the third time as he came back out from the dugout and acknowledged the crowd.
Brenly was drafted as an amateur free agent by the San Francisco Giants in 1976. He made his major league debut in 1981 at the age of 27. He replaced Milt May as the Giants starting catcher in 1983 and posted a .224 batting average along with 7 home runs and 34 runs batted in. Brenly had his best season offensively in 1984 when, he was hitting for a .318 batting average at mid-season to earn a spot as a reserve player for the National League in the 1984 All-Star game. He finished the season with a career-high .291 batting average with 20 home runs and 80 runs batted in. Brenly won the 1984 Willie Mac Award for his spirit and leadership.
Although Brenly was a good defensive catcher, he also has the dubious distinction of committing 4 errors in one inning while playing as a third baseman during a game on September 14, 1986, against the Atlanta Braves. Three of the errors were on ground balls and one on a throw, with the throwing error coming on the same play as one of the ground ball errors. Brenly atoned for his mistakes by hitting a fifth-inning home run. He then hit a two-out, two-runsingle in the seventh inning to tie the game and finally hit a walk-off home run in the bottom of the ninth inning to win the game. Brenly also was playing first base during a Giants-Mets game on September 3, 1986 when Keith Hernandez hit a sharp grounder to pitcher Terry Mulholland. The ball got stuck in Mulholland's glove so Mulholland tossed the glove with the baseball to Brenly for the out.
Brenly led National League catchers in 1987 with 83 assists and posted a .267 batting average with 18 home runs and 51 runs batted in as, the Giants won the National League Western Division title. In the only post-season appearance of his career in the 1987 National League Championship Series, Brenly hit .235 with 1 home run and 2 runs batted in as the Giants were defeated by the St. Louis Cardinals in a seven-game series.
During the 1988 season, Brenly caught only 69 games and would be released at the end of the season. In 1989, Brenly became a free agent and signed a contract to play for the Toronto Blue Jays. After half a season with the Blue Jays, he was released on July 18 and, re-signed to play for the Giants. After 12 games with the Giants, he retired at the end of the 1989 season at the age of 35.
In a 9-year career, Brenly played in 871 games, accumulating 647 hits in 2615 at bats for a .247 career batting average along with 91 home runs and 333 runs batted in. He ended his career with a .984 fielding percentage as a catcher.
He later returned to being a baseball analyst for Fox (where Brenly had worked from 1996 to 2000). He was then hired in November 2004 to replace Steve Stone as a color analyst for televised Chicago Cubs games. Brenly teamed with play-by-play announcer Len Kasper. He had previously teamed with Harry Caray, Thom Brennaman, and Ron Santo during the 1990 and 1991 seasons on radio. He often jokes about his mediocre playing career. Brenly is often referred to by his nickname, "BB" and was rumored to be in the running for several managerial positions for the 2008 season, though nothing materialized. Brenly was in the running for the 2009 Milwaukee Brewers managerial position and was said to be the favorite, but the job went to Ken Macha instead.
In 2007, Brenly served as a game analyst during postseason broadcasts on the TBS cable television network. He covered the Yankees–Indians series in the ALDS and the Rockies–Diamondbacks series in the NLCS. On September 13, 2008, Brenly signed a four-year extension worth 3.5 million dollars to continue his role as color analyst for Cubs games.
Brenly again worked Division Series post-season coverage for TBS in 2009-2012 with Dick Stockton as his play-by-play partner each year.
He opted out of an extension to his contract with the Cubs and WGN television on October 17, 2012. He looks to further his broadcast career in baseball. He will leave his Emmy award winning broadcast partner Len Kasper who signed an extension with WGN and Cubs last season.
On October 18, 2012, he signed a five-year deal as the TV color commentator for the Arizona Diamondbacks.
Bob Brenly is married to Joan Brenly. Their son Michael Brenly was drafted by the Cubs in 2004 (out of high school) and 2008 (out of UNLV) as a catcher. He played in the Chicago Cubs and Boston Red Sox Minor League systems in all or parts of eight seasons spanning 2008–2015. After retiring from the Portland Sea Dogs in May 2015, the younger Brenly took a position as the assistant bullpen catcher in the Boston organization.