Mattern, William
Current rating: 1522
Record: 21-20-1
| Grand Prix Phoenix 2017 (XLN limited) | starting rating: 1540 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 135 | Goetz, Adam (1561) | Lost 1-2 | -181522 |
| 2sealed | 162 | Schopf, Nickolas (1485) | Won 2-0 | +181540 |
| 3sealed | 162 | Bowman, Robert (1499) | Lost 0-2 | -191521 |
| 4sealed | 162 | Black, Grant (1479) | Won 2-0 | +171538 |
| 5sealed | 162 | Sulak, Andrew (1621) | Lost 0-2 | -161522 |
| top | average opponent: 1529record: 2-3 | new rating: 1522 | ||
| Grand Prix San Jose 2017 (AER limited) | starting rating: 1501 | |||
| round | table | opponent (rating) | result | Δrating |
| 3sealed | 232 | Avila, Matt (1638) | Won 2-1 | +211522 |
| 4sealed | 35 | Fortson, Kenneth (1521) | Won 2-1 | +181540 |
| 5sealed | 97 | Cordero Soriano, Carlos (1764) | Lost 1-2 | -141526 |
| 6sealed | 71 | Sun, Allen (1860) | Lost 0-2 | -131513 |
| 7sealed | 220 | Kim, Timothy (1537) | Won 2-1 | +191532 |
| 8sealed | 131 | Hollis, Jamey (1595) | Lost 0-2 | -171515 |
| 9sealed | 240 | Liswood, Jason (1519) | Won 2-0 | +181533 |
| 10draft | 250 | Kane, Will (1671) | Won 2-0 | +211554 |
| 11draft | 190 | Schmidt, Evan (1570) | Won 0-0 | +181572 |
| 12draft | 141 | Ganzler, Eric (1789) | Lost 1-2 | -141558 |
| 13draft | 166 | Blagg, Joshua (1554) | Draw 1-1 | 01558 |
| 14draft | 34 | Wang, John (1568) | Lost 1-2 | -181540 |
| top | average opponent: 1632record: 6-5-1 | new rating: 1540 | ||
| Grand Prix San Diego 2015 (ORI standard) | starting rating: 1520 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 308 | Rodriguez, Christopher (1500) | Won 2-0 | +171537 |
| 2standard | 275 | Thompson, Brad (1357) | Lost 0-2 | -211516 |
| 3standard | 494 | Ha, Raymond (1752) | Lost 1-2 | -141502 |
| 4standard | 508 | Laurtano, Michael (1482) | Won 2-1 | +181520 |
| 5standard | 439 | Cartlidge, Brandon (1468) | Lost 1-2 | -191501 |
| top | average opponent: 1512record: 2-3 | new rating: 1501 | ||
| Grand Prix Las Vegas 2015 (1) (MM2 limited) | starting rating: 1543 | |||
| round | table | opponent (rating) | result | Δrating |
| 1sealed | 76 | Sanders, Benjamin (1500) | Lost 0-2 | -181525 |
| 2sealed | 263 | Davis, Christopher (1444) | Won 2-0 | +161541 |
| 3sealed | 197 | Pierce, Elliot (1423) | Won 2-0 | +161557 |
| 4sealed | 129 | Loftus, Conor (1562) | Lost 0-2 | -181539 |
| 5sealed | 195 | Beckham, Zenaide (1466) | Lost 0-2 | -191520 |
| top | average opponent: 1479record: 2-3 | new rating: 1520 | ||
| Grand Prix Los Angeles 2014 (KTK standard) | starting rating: 1552 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 283 | Nguyen, Andrew (1500) | Lost 1-2 | -191533 |
| 2standard | 462 | Boyer, Blake (1481) | Won 2-1 | +171550 |
| 3standard | 436 | Carlstrom, Erik (1420) | Lost 1-2 | -201530 |
| 4standard | 640 | Chu, Terence (1443) | Won 2-1 | +161546 |
| 5standard | 519 | Power, Jason (1471) | Won 1-0 | +171563 |
| 6standard | 336 | Huang, Wesley (1484) | Lost 0-2 | -201543 |
| top | average opponent: 1467record: 3-3 | new rating: 1543 | ||
| Grand Prix Albuquerque 2013 (THS standard) | starting rating: 1500 | |||
| round | table | opponent (rating) | result | Δrating |
| 1standard | 233 | Green, Alex (1484) | Lost 1-2 | -181482 |
| 2standard | 328 | Maestas, Elesaio (1399) | Lost 0-2 | -201462 |
| 3standard | 451 | Ramirez, Michael (1485) | Won 2-0 | +191481 |
| 4standard | 447 | Garcia, Domicio (1482) | Won 2-1 | +181499 |
| 5standard | 391 | Boedder, Gene (1536) | Won 2-0 | +181517 |
| 6standard | 310 | Lynge, Alex (1468) | Won 2-0 | +171534 |
| 7standard | 234 | De La Court, Cameron J (1504) | Lost 1-2 | -181516 |
| 8standard | 273 | Selsing, Heather (1519) | Won 2-0 | +181534 |
| 9standard | 209 | Sackett, Benjamin (1544) | Won 2-1 | +181552 |
| top | average opponent: 1491record: 6-3 | new rating: 1552 | ||