Zimmer, nicknamed “Zim,” “Gerbil,” and sometimes “Popeye” because of his facial resemblance to the cartoon character, began his career in 1949 with the Cambridge Dodgers of the Class-D Eastern Shore League. He then played with the Hornell Dodgers of the Class-D PONY League in 1950, the Elmira Pioneers of the Single-A Eastern League in 1951, the Mobile Bears of the Double-A Southern League in 1952, and the St. Paul Saints of the Triple-A American Association in 1953 and 1954. He made his major league debut with the Brooklyn Dodgers in 1954. Zimmer’s big league career lasted 12 seasons, almost exclusively as a utility infielder. He played with 1955 World Series champion Brooklyn Dodgers, and with the 1962 New York Mets, who lost a record 120 games.

Immediately following his rookie season, Zimmer played winter ball in Puerto Rico, emerging as the decidedly dark horse Caribbean Series MVP on the heavy-hitting 1954-55 champion Cangrejeros de Santurce. Nicknamed Escuadrón del Pánico (lit. “Panic Squad”), the team featured future Hall-of-Famers Willie Mays and Roberto Clemente, future All-Stars George Crowe and Sam Jones, as well as Negro League stars Bob Thurman and Buster Clarkson. It was later described by Zimmer as “probably the best winter league baseball club ever assembled.”

While with St. Paul in 1953, Zimmer nearly died after being hit in the temple with a pitch. He was not fully conscious for 13 days, during which holes were drilled in his skull to relieve the pressure of swelling. His vision was blurred, he could neither walk nor talk and his weight plunged from 170 to 124. He was told his career was finished at age 22; fortunately for Zimmer, the prognosis proved incorrect and he made it to the major leagues the following year.

Zimmer was beaned again in 1956 when a Cincinnati Reds fastball broke his cheekbone, but he persevered. Because of these beanings, it has been widely reported that he had a surgically implanted steel plate in his head. This rumor is false, although the holes drilled in the surgeries following the 1953 beanball were later filled with four tantalum metal corkscrew-shaped “buttons.”

In the major leagues, Zimmer remained with the Los Angeles Dodgers after their move west in 1958. In 1960, the Dodgers traded Zimmer to the Chicago Cubs for Johnny Goryl, Ron Perranoski, Lee Handley and $25,000. After the 1961 season, the expansion New York Mets chose Zimmer from the Cubs as the fifth pick in the premium phase of the 1961 Major League Baseball expansion draft, costing the Mets $125,000. In May 1962, the Mets traded Zimmer to the Cincinnati Reds for Cliff Cook and Bob Miller. He returned briefly to the Dodgers in 1963, when the Reds traded him to the Dodgers for Scott Breeden. The Washington Senators purchased Zimmer from the Dodgers in June 1963. The Senators released Zimmer after the 1965 season, and he played for the Toei Flyers of Nippon Professional Baseball in 1966.

In 12 seasons, Zimmer played 1,095 games. He compiled 773 hits, 91 home runs, 352 RBI, 45 stolen bases and a .235 batting average. He played in the World Series with the Dodgers in 1955 and 1959, and was selected to the National League All-Star team in 1961. Although he had a low career batting average, Zimmer was regarded as a fine infielder, willing to fill in at third base, shortstop, and second base. He also caught 33 games in his final season with Washington in 1965.

Zimmer served as a player-manager for the Cincinnati Reds with the Double-A Knoxville Smokies and Triple-A Buffalo Bisons in 1967. Zimmer ended his playing career after the 1967 season, and he managed the Triple-A Indianapolis Indians in 1968. In 1969, he managed the Class-A Key West Padres and the Triple-A Salt Lake Bees in 1970.

In 1971, he joined the Montreal Expos as third base coach. He took a similar job with the San Diego Padres in 1972, but after only 11 games he was called on to replace Preston Gómez as manager, giving Zimmer his first managerial job in the major leagues.

After being fired by the Padres at the close of the 1973 campaign, he served as the third-base coach for the Boston Red Sox for 2½ seasons. Working under skipper Darrell Johnson, Zimmer’s tenure included a memorable event during Game 6 of the 1975 World Series. Boston had the bases loaded and none out in the home half of the ninth inning. The score was tied. A soft fly to left field was too shallow to score the winning run, but baserunner Denny Doyle thought Zimmer’s shouts of “No! No! No!” were actually “Go! Go! Go!” He ran for home, and was thrown out at the plate. That play, and Dwight Evans’ brilliant catch off Joe Morgan in extra innings, set up Carlton Fisk’s classic, game-winning home run.

The 1976 Red Sox never got on track under Johnson, and he was fired in July. Zimmer was named acting, then permanent, manager and he led them to a winning record, but a disappointing third-place finish in the AL East.  The Red Sox would win more than 90 games in each of Zimmer’s three full seasons (1977–1979) as manager, only the second time they had pulled off this feat since World War I. His 1978 team won 99 games, still the fourth-best record in franchise history.

However, he is best remembered among Red Sox fans for the team’s dramatic collapse during the 1978 season. After leading the American League East by as many as fourteen games, the Red Sox stumbled in August. By early September that lead was reduced to four games. That lead evaporated in a four-game series against the surging New York Yankees which is still known as “the Boston Massacre.”

The Red Sox spent the last month of the season trading first place with the Yankees, forcing a one-game playoff on October 2. In that game, the Yankees took the lead permanently on a legendary home run by Bucky Dent over the Fenway Park Green Monster.

During this stretch, Zimmer made several questionable personnel moves. He never got along with left-handed starting pitcher Bill “Spaceman” Lee. As a matter of fact, his outright hatred of Lee (who had nicknamed Zimmer “The Gerbil.”) ran so deep that he gave the starting assignment in the last game of the “Massacre” to rookie Bobby Sprowl, who had only been called up from Triple-A Pawtucket a few days earlier. Reportedly, Carl Yastrzemski pleaded with Zimmer to start Lee, who, along with Luis Tiant, had dominated the Yankees during their careers. (Lee, for example, won 12 out of 17 decisions against the Yankees in 10 years with Boston.) Sprowl allowed four walks, one hit and one run in the first inning before being pulled and made only three more major-league starts.

Zimmer also penciled Fisk, the team’s longtime starting catcher, into the lineup 154 times (out of a possible 162), a heavy workload for a catcher. Fisk complained of sore knees for much of this stretch and missed most of the next season with a sore arm. Finally, Zimmer kept third baseman Butch Hobson in the lineup, even though Hobson’s elbow miseries (he had floating bone chips which he frequently rearranged before coming to the plate) made it impossible for him to hit for power or average, or throw accurately. Hobson made error after error, until finally Zimmer called on Jack Brohamer to replace him; with Brohamer at third, Boston won its last eight games of the regular season to force a tie with the Yankees, but the Red Sox lost the playoff game on home runs by Dent and Reggie Jackson.

Zimmer next managed the Texas Rangers. He spent less than two years in the job and his firing by owner Eddie Chiles was different. Zimmer was fired on a Monday but asked to remain on through Wednesday’s game before being replaced by Darrell Johnson. When asked for the reason he fired Zimmer, Chiles said it was “something personal” but refused to elaborate further.

After Texas, Zimmer coached three stints with the Yankees (1983, 1986, 1996–2003), then coached for the San Francisco Giants in 1987. He served as third base coach for the Chicago Cubs from 1984–1986. In 1989, Zimmer managed the Cubs to a division title and was named Manager of the Year. Later, he returned to Boston for one season as a coach (under manager Hobson) in 1992. Overall, Zimmer won 906 Major League games as a manager.  Zimmer was on the first coaching staff of the expansion Colorado Rockies in 1993, and coached the Rockies through 1995.

In 1996, he joined the Yankees as their bench coach for their run of four World Series titles. In 1999, Zimmer filled in for Manager Joe Torre while Torre was recuperating from prostate cancer. Zimmer went 21-15 while guiding the Yankees during Torre’s absence. This record, however, is credited to Torre’s managerial record. Many fans know him for his “brawl” with Pedro Martínez in the 2003 American League Championship Series, when Zimmer ran at Martinez and Martinez threw Zimmer to the ground. He was also once hit by a sharply hit foul ball batted by Yankee second baseman Chuck Knoblauch. The next game, Zimmer wore an army helmet with the word “ZIM” painted on the side and the Yankees logo stenciled on the front. That event led to the installation of fences in front of the dugouts at Yankee Stadium, which eventually became commonplace at most MLB ballparks.

Zimmer was a senior advisor for the Tampa Bay Rays. His role included assisting the team during spring training and during home games. Every year, Zimmer incremented his uniform number by one to match the number of years he has worked in baseball. During the 2014 season he wore #66, as seen on the Rays’ official site. Zimmer often noted that every paycheck he’d ever gotten came from baseball, and that he never held a job in any other profession.  Zimmer wrote two books, Zim: A Baseball Life, and The Zen of Zim, that describe his life in baseball, as a player, manager, and coach.

From the 2008 season to his death, Zimmer was the last former Brooklyn Dodger (besides announcer Vin Scully) still serving on the field in some capacity. Zimmer also served as a member of the advisory board of the Baseball Assistance Team, a 501(c)(3) non-profit organization dedicated to helping former Major League, Minor League, and Negro League players through financial and medical difficulties.

At home plate before an Elmira night game in 1951, Zimmer married Soot (Carol Jean Bauerle), whom he started dating in 10th grade. Until his death in June 2014, they were still married and lived in Seminole, Florida. They had lived in the Tampa Bay Area since the late 1950s.  Zimmer’s son Thomas is a scout with the San Francisco Giants. He also has a daughter, Donna, and four grandchildren.  Zimmer’s grandson Beau works as a reporter at WTSP 10, St. Petersburg, Florida.  In December 2008, Zimmer suffered a stroke, causing loss of speech for a week.  Zimmer died at age 83 on June 4, 2014, in Dunedin, Florida, from heart and kidney problems.