John Marks has found grass courts difficult, recording 19–32 across 51 matches (37.3%). The numbers point to a surface that has not consistently suited the game — a key area of opportunity on the calendar. John Marks has reached 2 finals without yet claiming a title on grass — one of the finest margins in tennis.

At Grand Slam level (Wimbledon): John Marks is 6–9 (40.0%) across 15 Grand Slam matches — below .500, though the elite draw depth at the Slams makes that a notoriously difficult barrier to crack.

2 finals reached on grass — none converted into a title yet. Reaching 2 finals is a mark of real quality, but the gap between finalist and champion is one of the finest lines in the sport. 2 semifinals. 2 quarterfinals.

By format on grass — best-of-five: 6–10 (37.5%); best-of-three: 13–22 (37.1%). Consistent regardless of format on grass — a sign of a well-rounded game that holds up as matches develop.

Best season: 1975 — 5–1 (83.3%) from 6 matches. The best single-season display to date — a useful reference point as the grass record continues to develop.