[3] Among Hertl's advantages include his large body and a good physical and defensive play, which Muir compared to Martin Hanzal.

[6] In the preseason, Hertl scored 3 goals and 1 assist, and joined Joe Thornton and Brent Burns on a line, filling the hole created by Raffi Torres' injury.

[5] Hertl made his NHL debut against the Vancouver Canucks on 3 October,[7] 2013 and tallied his first career point with an assist on a goal by Brent Burns.

[13] However, on 19 December against the Kings, Hertl injured his knee after a collision with Dustin Brown and was reported to miss at least a month.

[17] On 29 June 2016, at the conclusion of his entry-level contract, Hertl agreed to a two-year, $6 million extension to remain with the Sharks.

Following this, the Sharks beat the Colorado Avalanche, also in seven games, before being defeated by the St. Louis Blues in the Western Conference Finals.

[21] In January 2020, Hertl participated in the 2020 National Hockey League All-Star Game as an alternate following an injury to teammate Logan Couture.

[26] Hertl joined the Czech Republic at the 2011 IIHF World U18 Championships, scoring one goal, as the team finished eighth.

The next year, Hertl participated in the 2012 World Junior Ice Hockey Championships for the Czechs, scoring three goals and two assists, with the team finishing fifth.

[28] Due to the knee injury against the Kings in December 2013, Hertl was forced to have surgery and missed out on participating in the 2014 Sochi Olympics.