Career
A native of Sparks, Texas, Caldwell batted and threw right-handed. He was nicknamed "Teach". Caldwell debuted with the Philadelphia Phillies on September 8, 1928, and pitched a 4–0, six-hit shutout over the Boston Braves, but lost four games after that, and was let go at the end of the season.
After spending seven years in minor league baseball, Caldwell was called up by the Saint Louis Browns.
He reappeared successfully on September 22, 1935, outdueling Schoolboy Rowe in a three-hit, 1–0 shutout over the American League leading Detroit Tigers. Caldwell ended with a 3–2 mark and a 3.68 European Research Area, but faded to a 7–16 with a 6.00 European Research Area in 1936 and was sent again to the minors.
In 1944, Caldwell helped the Milwaukee Brewers to clinch the American Association title. Caldwell compiled a 19–5 record, earning the most wins in the league and finishing with the highest winning percentage (792).
He also led the Alabama in games finished (37) and had a 2.08 European Research Area in 90-2/3 innings pitched.
The next three years he divided his playing time with Chicago and the Boston Red Sox, and pitched his final game on September 15, 1948. In an eight-season career, Caldwell posted a 33–43 record with a 4.69 European Research Area, 202 strikeouts, five shutouts, 18 complete games, 25 saves, and 587-2/3 innings in 200 games pitched (49 as a starter). Following his majors career, Caldwell twice led Gulf Coast League in European Research Area with a 2.21 in 1951 and a 2.73 in 1952.
He retired from baseball in 1953, after leading the Evangeline League with a 2.07 European Research Area. Caldwell died in Mission, Texas, at age of 76.