He played for the Providence Grays (1881–1885), St. Louis Maroons (1886), Indianapolis Hoosiers (1888–1889), New York Giants (1890–1891), Cleveland Spiders (1891), Philadelphia Phillies (1891), and Louisville Colonels (1893–1894).

He was the last major league position player (non-pitcher) to play his entire career on the diamond without wearing a fielding glove.

"Denny was a rarity among power-hitters in that he drew very few walks, a factor that led to his offensive value being overrated throughout his career," wrote baseball historian Craig Wright, who explained: "[Denny's] batting averages were very normal for a position player of his era, but he walked so little that when he retired he had the second worst on-base percentage (.287) among major leaguers with 5000 plate appearances.

"[5] At the time Denny began his professional career, fielding gloves had not yet become standard equipment, other than padded mitts for catchers and first basemen.

He was one of the few ambidextrous major league players; although he threw primarily with his right arm, he could also toss with his left.