match darts in the third round of the Players Championship Finals as Chisnall edged through 10–9. 2017 He got to the third round of the World Championship for the second year in a row with comfortable victories over Jeffrey de Graaf and Brendan Dolan, but found himself 3–1 down to Dave Chisnall. Klaasen took the next set and led by two legs to none in the sixth, before Chisnall won three legs on the spin to triumph 4–2. His return to the Premier League was blighted by tendinitis in his wrist for which Klaasen received anti-inflammatory injections before matches. Klaasen explained how he could play for five or six legs before experiencing pain in his throwing hand. His only win out of his nine league games came against Chisnall and Klaasen finished ninth in the table to be eliminated. He lost 6–2 in the final of the German Darts Masters to Van Gerwen. 2018 At the 2018 PDC World Darts Championship, Klaasen was defeated by Jan Dekker 3–1 in the first round. He was defeated 10–5 by Peter Wright in the opening round of the World Matchplay. 2019 At the 2019 PDC World Darts Championship, Jelle was defeated by Keegan Brown 3–1 in the second round. He lost in the fourth round of the UK Open to Madars Razma 10–4. He then qualified for his first euro tour of the year 2019 International Darts Open, losing in the first round to Joe Murnan 6–5. He then lost in the Players Championship Finals to Max Hopp 6–3. 2020 Klaasen beat Kevin Burness 3–1 in the first round of the 2020 PDC World Darts Championship, before losing to Michael van Gerwen by the same scoreline. At the 2020 UK Open, he started his campaign by defeating Riley's qualifier Jason Askew 6–4. Klaasen then beat William Borland 10–5 before thrashing Steve West 10–1 to set up a sixth-round clash with Gary Anderson. He overcame Anderson 10–9 before losing in the quarter-finals to Daryl Gurney. WDF Career From the beginning of 2022, Klaasen took part in tournaments organized by the World Darts Federation. In June 2022, he took part in the Dutch Open, where he was seeded in 26th. On his way to the final of this tournament, he defeated leading WDF players including Richard Veenstra and Thibault Tricole, before defeating Mark Barilli in the final. This qualified him for the 2023 WDF World