Cost, John Sebastian
Current rating: 1484
Record: 2-3
| Grand Prix Portland 2018 (modern) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 531 | Harlow, Nic (1601) | Won 2-0 | +201520 |
| 2modern | 254 | Barrus, Travis (1481) | Won 1-0 | +171537 |
| 3modern | 37 | LeBlanc, Joseph (1538) | Lost 0-2 | -181519 |
| 4modern | 453 | Means, Charles (1521) | Lost 0-2 | -181501 |
| 5modern | 470 | Levchak, Tavis (1567) | Lost 0-2 | -171484 |
| average opponent: 1541record: 2-3 | new rating: 1484 | |||