Gyokeres, a 63.5-million-pound off-season signing from Sporting CP, has been ever-present for the Gunners this season, starting all but one match across all competitions.
He has netted three goals so far, including a brace against newly promoted Leeds back in August, but is currently enduring a six-game goal drought.
Some pundits have questioned his impact when not finding the net, but Tomasson dismissed such doubts, insisting that critics "don't understand football." The Sweden boss praised Gyokeres's all-round contribution, emphasising his work rate and ability to create space for teammates.
Despite the criticism, the 26-year-old striker has retained his place in Sweden's squad for their upcoming World Cup qualification double header against Switzerland and Kosovo.
"Viktor Gyokeres is in very good form at the moment and is very good," said Tomasson.
"If people say he doesn't have an impact (on matches), then they don't understand football and don't have a clue about football. He creates space for other players, works on the ball and makes runs.
"It's excellent and he scores goals almost all the time, so he has an impact and has been very good. It's always nice, as you need time when you come to a new club."
Sweden are under pressure after a disappointing run of results - drawing with Slovenia and suffering a defeat to Kosovo last month - which leaves them trailing Switzerland in Group B. The Swiss, meanwhile, boast a 100 percent record after two games.
Mikel Arteta has described Granit Xhaka as "one of the signings of the season" ahead of Arsenal's reunion with their former midfielder when they face Sunderland at the Stadium of Light on Saturday.
Arsenal's Premier League momentum has taken a hit after star striker Viktor Gyokeres suffered a hamstring injury that will rule him out of Saturday's trip to Sunderland.
Alphonso Davies is edging ever closer to a full return for Bayern Munich following a lengthy recovery from a cruciate-ligament injury sustained in March.
Arsenal defeated Slavia Praha 3-0 in Prague as North London rivals Tottenham Hotspur hammered Copenhagen 4-0 at the Emirates Stadium on Tuesday.
