Kellman went 8-for-20 (.400) to lead the Buckeyes in the Series, though they featured future big leaguers as Trouppe, Al Smith and Sam Jethroe (.316), who was the only other player over .300.

[10][11] In 1951 Kellman journeyed to Mexico, where he enjoyed a solid season with the Azules de Veracruz, batting a slash line of .292/.407/.450, which included 10 home runs in 271 at-bats,[12] helping the team to clinch the championship.

[13] After that Kellman returned to the Negro leagues, dividing his playing time with the Memphis Red Sox and Indianapolis Clowns in 1952 and part of 1953,[14] when he came back to Mexico and joined the Tecolotes de Nuevo Laredo for the rest of the year, batting .268 in 79 games.

[15] In addition, Kellman became the first player in Mexican baseball history to hit two grand slams in the same game, accomplishing his feat against the Diablos Rojos de México on May 5, 1954.

After that, he was added as a reinforcement of the Carta Vieja Yankees in 1952 and the Chesterfield Smokers in 1953, while managing his Cerveza Balboa champion team to a second-place finish (3–3) behind Cuba's Tigres de Marianao (5–1) in the 1957 Series.

Kellman retired with a career average of .297 in the Panamanian league and batted .205 (9-for-44) in five Caribbean Series, while tying with teammate Sam Bankhead and Cuba's Chuck Connors for the most stolen bases with four during the inaugural tournament.

His early efforts would enable future generations of fellow countrymen to follow him, including Humberto Robinson, the first Panamanian-born big leaguer, as well as Rod Carew, Webbo Clarke, Héctor López, Ben Oglivie, Mariano Rivera, Carlos Ruiz, Manny Sanguillén and Pat Scantlebury, among many others.