[5] After completing his education, Alexander was employed digging postholes for the Howard County Telephone Company.

[6] Alexander played semi-professional baseball in his youth, signing his first professional contract at age 20 in 1907 for $50 per month ($1,635 in current dollar terms).

[7] Alexander made his Philadelphia Phillies debut during the pre-season 1911 City Series, pitching five innings of no-hit, no-run baseball against the Athletics.

[8] He was joined on the Phillies that year by catcher Bill Killefer, who went on to become Alexander's favorite battery mate, catching 250 of his games.

In 1915, he was instrumental in leading the Phillies to their first pennant,[2] pitching a record five one-hitters and winning his only Major League triple crown.

While he was serving in France, he was exposed to German mustard gas and a shell exploded near him, causing partial hearing loss and triggering the onset of epilepsy.

[15] Following his return from the war, Alexander suffered from shell shock and was plagued with epileptic seizures, which people often misinterpreted as a sign of drunkenness; this only exacerbated his drinking problem.

In spite of all this, Alexander gave Chicago several successful years and won another pitching triple crown in 1920.

Tiring of his increasing drunkenness and insubordination that was often directly related to his epilepsy, the Cubs sold him to the Cardinals in the middle of the 1926 season for the waiver price.

[16] Alexander came into the game in the seventh inning after starter Jesse Haines developed a blister, with the Cardinals ahead 3–2, the bases loaded and two out.

In the 1940s, Mathewson was discovered to have qualified for an additional victory (May 21, 1912) and his total was officially upped to 373 and into a tie with Alexander.

Alexander played with and against many of the Negro league stars of the day, including Satchel Paige,[18] John Donaldson, Newt Joseph,[18] Chet Brewer, and Andy Cooper.

[citation needed] After the end of prohibition, Alexander operated a tavern in St. Louis with Hughie Miller as his partner.

When he won his 373rd game on August 10, 1929, one newspaper had called him "old Pete", indicating that the nickname was in public circulation.