Jimmy Key played his entire career in the American League East, dividing between three teams, Toronto, New York, and Baltimore, finding success with all three clubs.

Key’s foray into the Majors first came with the Blue Jays, where he was used in late relief as a rookie.  That year ended his bullpen days, as Toronto promoted him to the starting rotation, and he was an All-Star.  Key would remain an essential figure in the Jays’ staff, winning the ERA Title in 1987 when he was the runner-up for the Cy Young.  Key was again an All-Star in 1991, and the following year, he helped take the Jays to their first World Series win.

Key was not in Toronto in 1993 to defend their title as he joined their rival, New York, as a Free Agent.  The Pitcher went to have the best back-to-back years of his career, earning All-Star nods in pinstripes in both '93 and '94, and finishing fourth and second in Cy Young voting, respectively.  In that runner-up year, he led the AL in Wins (17) and was also sixth in MVP voting. 

In his final two years in baseball (1997 & 1998), he was with Baltimore and was an All-Star in what was his penultimate year.  Key left the game with a 186-117 record.

Claude Passeau appeared in one game in 1935 for the Pittsburgh Pirates, and the three innings he had shown nothing that would make you think he would be a future All-Star.

Passeau won a regular role with the Philadelphia Phillies, where he lost more games than he won, but he was a serviceable Pitcher and worthy of a Major League roster spot, and his advanced metrics were very good.

During the 1939 season, Passeau was traded to the Chicago Cubs, and his fortunes changed.  Passeau was second that season in bWAR for Pitchers (6.0) and eighth in ERA (3.28), and in 1940, his first full year as a Cub, he was first in bWAR for Pitchers (6.9) and second in ERA (2.50).  He won 20 Games that year and was named an All-Star five of the next six years; except for the last year of that run (1946), he always had at least 14 Wins and had four years with a sub-3 ERA.   

Passeau was a vital cog in the Cubs team that won the 1945 National League Pennant. In the World Series, he pitched a one-hitter, but the Cubs lost the series to the Detroit Tigers.

Frank McCormick debuted for the Cincinnati Reds in 1934, and this was the team for which he had his greatest success by far.

McCormick became their starting First Baseman in 1938, and he began a nine-year streak of All-Star seasons.  From ’38 to ’40, a case could be made that McCormick was the best hitter in the National League.  In all of those seasons, the New Yorker led the NL in Hits and batted over .300, had over 100 RBIs, and was in the top five in MVP voting, including a win in 1940.

The Reds had also put it all together at this time, and they won the National League Pennant in both 1939 and 1940.  In the former World Series, McCormick batted .400, but the New York Yankees swept the Reds.  In the MVP year of 1940, McCormick was not as effective, but Cincinnati beat Detroit in seven.

The First Baseman remained a quality player throughout the first half of the 40s, gaining two more .300 years, and stringing together MVP votes annually from 1942 to 1946.  McCormick was traded to the Philadelphia Phillies in 1946, and that was his last All-Star year.  He played two more seasons with the Boston Braves, finishing his career with 1,711 Hits and a lifetime Batting Average of .299.

One of the most underrated players in Baseball's history has to be George Uhle, a Pitcher who spent most of his career with the Cleveland Indians and won an even 200 Games.

Debuting for Cleveland in 1919, Uhle was a member of the Indians’ World Series Championship team in 1920, albeit in a minor role.  Following that, Uhle became the Tribe's staff ace, posting three 20-Win seasons, with two of those years being league-leading.  One of his claims to fame is that he deliberately walked a batter to pitch to Babe Ruth (he struck him out).  In fact, he struck out Ruth 25 times, the second-most of any Pitcher.   

Uhle was also an excellent hitting Pitcher, with a lifetime Batting Average of .289, and would occasionally be used as a Pinch Hitter.  Uhle would later play for Detroit and both New York teams.