Tom Okker has an impressive clay court record of 207–75 across 282 matches (73.4% — strong). A win rate of that calibre over 282 matches is a reliable indicator of genuine quality on this surface. With 14 titles, among the most prolific clay court champions in the Open Era: Barranquilla, Rome, Monte-Carlo, Brussels and 7 more.

At Grand Slam level (Roland Garros): a positive 12–5 (70.6%) across 17 matches — a player who generally rises to the occasion at the Slams on clay.

26 finals reached on clay — won 14, lost 12 (solid 54% conversion) — consistently getting to finals and winning the majority is a hallmark of elite performers on clay. 34 semifinals. 50 quarterfinals.

vs. Top 10 on clay: 3–6 (33.3%, 9 matches). Top 10 opponents have represented a clear ceiling on clay; addressing that deficit is the single biggest lever for improving the overall record here.

By format on clay — best-of-five: 63–25 (71.6%); best-of-three: 144–50 (74.2%). Slightly stronger in three-set contests on clay, though the five-set record is still respectable.

Dominant season: 1969 — 40–5 (88.9%) from 45 matches. A campaign of 40 wins on clay in a single season is among the best single-season records the surface has seen — the clearest benchmark of what is achievable at peak level.