Rodenburg, Kostek
Current rating: 1510
Record: 6-6
| Grand Prix Brussels 2020 (pioneer) | starting rating: 1529 | |||
| round | table | opponent (rating) | result | Δrating |
| 1pioneer | 234 | Locciola, Simone (1500) | Lost 0-2 | -181511 |
| 2pioneer | 579 | van Doorn, Lorenzo (1403) | Won 1-0 | +161527 |
| 3pioneer | 692 | Caffi, Giovanni Battista (1501) | Won 2-0 | +171544 |
| 4pioneer | 270 | Hills, Nathan (1687) | Lost 1-2 | -151529 |
| 5pioneer | 535 | Winkler, Florian [AUT] (1470) | Lost 1-2 | -191510 |
| average opponent: 1512record: 2-3 | new rating: 1510 | |||
| Grand Prix Utrecht 2019 (ELD limited) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 403 | Lea, Roszjar (1500) | Won 2-0 | +181518 |
| 2sealed | 359 | Held, Marco (1657) | Won 2-0 | +211539 |
| 3sealed | 307 | Box, Jesper (1920) | Won 2-1 | +241563 |
| 4sealed | 111 | Golovko, Ivan (1786) | Lost 1-2 | -141549 |
| 5sealed | 301 | Ciotta, Andrea (1731) | Lost 0-2 | -151534 |
| 6sealed | 391 | Warembourg, Romain (1347) | Won 2-0 | +151549 |
| 7sealed | 168 | Dziegel, Eric (1449) | Lost 0-2 | -201529 |
| average opponent: 1627record: 4-3 | new rating: 1529 | |||