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. 

Historically speaking, one of the most important Pitchers in Latin America is Dennis Martinez, and he was also among the longest-tenured.

Martinez broke in with the Baltimore Orioles in 1976, and he became the first player from Nicaragua to make the Majors.  The righthander did well, earning a place in the starting rotation and had five 14-win seasons for the O's, including a league-leading 14 in the strike-shortened 1981 season.  Martinez finished fifth in Cy Young voting that year, but he had an awful 1983 season, with an ERA well over 5.  He was left off of the postseason roster, and the Orioles won the World Series. Martinez continued to struggle, and it was learned that he was a heavy drinker, and alcoholism threatened to end his career early.

The Nicaraguan got clean, but he didn't have time to focus on both pitching and sobriety, and a change of scenery in the form of a 1986 trade to Montreal was just the tonic he needed.  With the Expos, Martinez went to three All-Star Games, won the ERA Title in 1991 (2.39), and had five top-ten finishes in bWAR for Pitchers.  

At age 40, Martinez signed with the Cleveland Indians to have another All-Star year amongst the three he played in Ohio.  He carved out two more years, one with Seattle and one with Atlanta, and Martinez retired with 245 Wins, which at the time placed him first among all Hispanic Pitchers,

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Eddie Rommel played his entire 13-year playing career with the Philadelphia Athletics (1920-32), where he became one of the first masters of the knuckleball.

After Rommel’s rookie year, he would become a workhorse for the Athletics, leading the American League in Wins twice (1922 & 1925) and Games Pitched (1922 & 1923).  His best year was in 1922, when he went 27-13 with a 3.28 ERA and a second-place finish in MVP voting.  Philadelphia became an AL power by the end of the decade, but by that time, Rommel was no longer the same Pitcher.  He would, however, come out of relief to win a game in the 1929 World Series, which was won by Philadelphia. 

Rommel would later have a successful career as an umpire, which included working in the 1943 and 1947 World Series.

Rudy York was best known for his time with the Detroit Tigers, where he had his greatest success.

York had a cup of coffee with Detroit in 1934, and he returned to stay in 1937, with a 35-home-run year, which would be a career high.  Eighteen of those taters took place in a month, breaking Babe Ruth’s record.  York continued to blast homers, winning the Home Run Title with 34 in 1943, while also leading the American League in Runs Batted In (118).  York finished third in MVP voting that year, and he had eight other seasons where he received an MVP vote.  

The seven-time All-Star also played for Boston, Chicago (AL), and Philadelphia (AL), and he had 277 career Home Runs.