Hjersman, Johannan
Current rating: 1630
Record: 27-19-1
| Grand Prix Oakland 2019 (modern) | starting rating: 1647 | |||
| round | table | opponent (rating) | result | Δrating |
| 1modern | 207 | Rovegno, Kevin (1590) | Lost 1-2 | -191628 |
| 2modern | 303 | Samek, Jessy (1512) | Lost 0-2 | -201608 |
| 3modern | 544 | Wingard, Nolan (1463) | Won 2-0 | +151623 |
| 4modern | 466 | Gutierrez, Abel (1353) | Won 2-0 | +131636 |
| 5modern | 408 | Markel, Eric (1595) | Lost 1-2 | -181618 |
| 6modern | 339 | Bordwell, Christopher (1457) | Won 2-0 | +151633 |
| 7modern | 306 | Lister, Chloe (1515) | Won 2-0 | +161649 |
| 8modern | 191 | Vaughn, Collin (1616) | Lost 1-2 | -191630 |
| top | average opponent: 1513record: 4-4 | new rating: 1630 | ||
| Grand Prix Sacramento 2018 (M19 limited) | starting rating: 1675 | |||
| round | table | opponent (rating) | result | Δrating |
| 3sealed | 342 | Smyth, Jason (1870) | Won 2-1 | +221697 |
| 4sealed | 66 | Ho, Anthony (1614) | Lost 1-2 | -201677 |
| 5sealed | 226 | Saltzman, Ryan (1627) | Won 2-0 | +171694 |
| 6sealed | 117 | Gates, Cody (1576) | Won 2-1 | +161710 |
| 7sealed | 19 | Hibbard, Dalton (1677) | Lost 1-2 | -181692 |
| 8sealed | 167 | Engle, Woodrow (1806) | Won 2-0 | +201712 |
| 9sealed | 53 | Hu, Shengling (1792) | Won 2-1 | +191731 |
| 10draft | 88 | Weitz, Benjamin (1947) | Lost 1-2 | -141717 |
| 11draft | 91 | Rodrigues, Dante (1521) | Lost 0-2 | -221695 |
| 12draft | 13 | Ma, Yuchen (1546) | Lost 0-2 | -201675 |
| 13draft | 107 | Kogen, Eric (1543) | Lost 1-2 | -211654 |
| 14draft | 86 | Nuccio, John (1378) | Won 2-1 | +131667 |
| 15draft | 83 | Nelson, Colleen (1530) | Lost 0-2 | -201647 |
| top | average opponent: 1648record: 6-7 | new rating: 1647 | ||
| Grand Prix San Jose 2017 (AER limited) | starting rating: 1537 | |||
| round | table | opponent (rating) | result | Δrating |
| 3sealed | 86 | Newbom, Aaron (1548) | Lost 1-2 | -181519 |
| 4sealed | 327 | Pilgrim, Zac (1505) | Won 2-0 | +181537 |
| 5sealed | 189 | Freytag, Eric (1530) | Lost 1-2 | -181519 |
| 6sealed | 358 | Perry, Gavin (1538) | Won 2-0 | +181537 |
| 7sealed | 214 | Skallerup, Josiah (1574) | Won 2-1 | +191556 |
| 8sealed | 180 | Tartaglio, Paul (1468) | Won 2-1 | +161572 |
| 9sealed | 133 | Stone, Jeffrey (1717) | Won 2-1 | +211593 |
| 10draft | 181 | Magana, Jesus (1754) | Won 2-1 | +211614 |
| 11draft | 176 | Horwitz, Lucas (1673) | Won 0-0 | +191633 |
| 12draft | 123 | Wong, Daniel (1717) | Won 2-0 | +191652 |
| 13draft | 114 | Hawklyn, Scott (1657) | Won 2-1 | +181670 |
| 14draft | 84 | Aguilera, Ryder (1876) | Lost 0-2 | -141656 |
| 15draft | 78 | Honea, John (1719) | Won 2-1 | +191675 |
| top | average opponent: 1637record: 10-3 | new rating: 1675 | ||
| Grand Prix San Diego 2015 (ORI standard) | starting rating: 1541 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 325 | Nail, Chavez (1500) | Won 2-0 | +171558 |
| 2standard | 46 | Shum, Jeska (1518) | Draw 1-1 | -11557 |
| 3standard | 319 | Miller, Iann (1501) | Won 2-1 | +171574 |
| 4standard | 172 | Brown, Derek (1502) | Lost 1-2 | -191555 |
| 5standard | 320 | Winter, Dillon (1551) | Lost 1-2 | -181537 |
| top | average opponent: 1514record: 2-2-1 | new rating: 1537 | ||
| Grand Prix Las Vegas 2015 (2) (MM2 limited) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 22 | Stokes, Nicholas (1488) | Won 2-0 | +181518 |
| 2sealed | 153 | Bulthaup, Sean (1724) | Won 2-1 | +211539 |
| 3sealed | 208 | Greathouse, Robert (1645) | Lost 1-2 | -161523 |
| 4sealed | 240 | Khan, Alec (1645) | Won 2-1 | +211544 |
| 5sealed | 199 | Mohd Shuhaimi, Nik (1462) | Lost 1-2 | -201524 |
| 6sealed | 262 | Collins, Jason (1605) | Won 2-1 | +201544 |
| 7sealed | 207 | Jones, Matt (1320) | Won 2-1 | +141558 |
| 8sealed | 134 | Ho-Ten-Pow, Marino (1625) | Lost 0-2 | -171541 |
| top | average opponent: 1564record: 5-3 | new rating: 1541 | ||