With a five-year record of 29–5, he has the highest winning percentage of any football coach in Michigan State history.

He was also the athletic director at Michigan Agricultural and coached the school's basketball, baseball, and track and field teams.

[4] When Macklin arrived at Penn, one account indicates there were no uniforms large enough to fit him: "When the big husky appeared on the gridiron the first thing the coaches did was to send for the athletic outfitter, for there was not a suit on the campus that would encompass his frame.

The Chicago Daily Tribune later wrote: "For a big man he was remarkably agile and his tackling on the wings and his quickness in getting through to break up plays was the delight of the coaches.

[8] Macklin's 1913 Michigan State team finished with an undefeated, untied record of 7–0 and outscored opponents by a combined score of 180 to 28.

[10] Macklin was also the athletic director and coach of the baseball,[11] men's basketball, and track and field teams.

[13] The Associated Press in 1949 called Macklin "the founding father of the big time at Michigan State College.