As there were no full-time base coaches at the time, players took turns in the role. While coaching at third base, Seymour tackled teammate Moose McCormick as he rounded third base and headed for home plate, in an attempt to keep McCormick at third. McCormick overpowered Seymour and scored. When McGraw asked why, Seymour made an excuse about having the sun in his eyes. This led McGraw, now realizing the need for a full-time coach, to hire Arlie Latham for the role, the first full-time coach in MLB. Seymour got into an altercation with Latham in March 1909 at the team's hotel, prompting McGraw to seek a buyer for Seymour. Seymour apologized to McGraw, who responded by suspending Seymour for eight weeks. However, Seymour injured his right leg in his first game back from the suspension. This injury limited his effectiveness for the rest of his career. As a part-time player that season, he batted .311, best among NL reserves. He again played a reserve role for the Giants in 1910, batting .265 in 79 games.