Jan Siemerink has a competitive grass court record of 28–32 across 60 matches (46.7%). The record shows a player capable of competing here, though there is clear room to push the win rate higher. Claimed 1 title on grass: Nottingham.

At Grand Slam level (Wimbledon): Jan Siemerink has struggled at Grand Slam level on grass: 6–10 (37.5%) in 16 matches. The best-of-five format and elite fields make this the toughest benchmark on this surface.

One final reached on grass, converted into a title — a perfect finals record on this surface. 2 semifinals. 5 quarterfinals.

vs. Top 10 on grass: 2–4 (33.3%, 6 matches). Top 10 opponents have represented a clear ceiling on grass; addressing that deficit is the single biggest lever for improving the overall record here.

By format on grass — best-of-five: 6–12 (33.3%); best-of-three: 22–20 (52.4%). Markedly stronger in three-set formats; the win rate drops noticeably in five-setters, which has direct implications for Grand Slam performance on grass.

Best season: 1998 — 8–3 (72.7%) from 11 matches. The best single-season display to date — a useful reference point as the grass record continues to develop.