[1][2] Petralli made his professional debut in 1978 with the Medicine Hat Blue Jays of the rookie Pioneer Baseball League, where he batted .281 in 65 games, playing some third base as well as catching.

Petralli was promoted back to Syracuse in 1981, where he split time with fellow catching prospects, Dan Whitmer and Ramón Lora, and appeared in just 45 games and batted .265.

With Ernie Whitt and Martinez still around to handle catching duties for Toronto, and designated hitter Cliff Johnson available for emergencies, Petralli returned to Syracuse in 1983.

In 1984, Petralli made the major league roster out of spring training, but appeared in just three games over the first month of the season, batting three times without a hit.

There, he served as backup to former New York Yankees prospect Juan Espino, playing in just 23 games and batting .217 without a home run.

[6] Petralli finished the season with what were, to that point, career highs in most categories, including his first major league stolen base.

[7] On July 13, Petralli hit his first major league home run against Indians starter and future Hall of Famer Phil Niekro as the Rangers won 5–3.

[8] His only other home run of the year was a big one, a game tying two-run pinch-hit home run in the bottom of the eighth inning off Roger Clemens during a nationally televised Monday night baseball game against the first place Boston Red Sox on August 25, 1986, at Arlington Stadium.

[11] Petralli, who served as the Rangers' Union Player Representative in 1986, once again bettered his career highs to date that year.

The first came on August 22, as Petralli committed four passed balls in one inning to tie the major league record Ray Katt had set while catching knuckleballer Hoyt Wilhelm in 1954.

[12] The record was later tied by Ryan Lavarnway of the Boston Red Sox in 2013, catching knuckleballer Steve Wright in his first major league start.

[14] Offensively, Petralli continued to improve, as he became the first catcher in Rangers franchise history to bat over .300,[15] posting a .302 average.

On November 2, 1987, the Rangers traded Don Slaught to the Yankees for pitcher Brad Arnsberg, and on December 21 they released Porter,[16] leaving Petralli and Stanley as the team's top two catchers for the 1988 season.

When Stanley came back, the Rangers continued to carry three catchers, and in September they again added a fourth, bringing prospect Chad Kreuter up from the minors.

[17] He opened the 1989 season as the Rangers primary starting catcher for the first time, although Stanley, Sundberg and Kreuter remained with the team as well.

At the end of May, after the team released Buddy Bell, Petralli was moved to designated hitter, with Kreuter and Sundberg taking over catching duties.

Sundberg had retired after the 1989 season, and Stanley was named Petralli's backup while also spending time at DH and first base.

[20] Back in a full-time role for the entire season catching Hough, Petralli led all of Major League Baseball in passed balls for the third time in four years, matching his 1988 total of 20.

When Petralli came back at the end of July, he found himself relegated to backup catcher, with occasional duty at DH and as a pinch hitter.

In 59 games at catcher, DH, and the infield, Petralli bounced back to hit .241, although that was still the second-lowest average of his career.

His final major league game came on Saturday October 2, 1993, in front of over 41,000 fans as the Rangers lost to Tom Gordon and the Kansas City Royals by a score of 7–4.

He was first chosen by the Los Angeles Dodgers in 2004, but chose to play at his father's alma mater, Sacramento City College.