The Blues defender put 13 months without league football behind him with a return at Peterborough on Saturday.
Whatmough was thrown in at London Road with just one Leasing.com Trophy over six weeks ago to his name since returning from a knee injury.
It proved a tough challenge as the 23-year-old was tasked with taking on League One’s top scorer Ivan Toney and the division’s highest-scoring side.
Whatmough was withdrawn at the interval on a booking, but Kenny Jackett feels the outing will help his Pompey comeback gather pace.
He said: ‘Jack has worked hard and waited patiently.
‘He’s worked very hard and had a heavy workload to get back
‘He’s fine, though and he’s okay. He’ll benefit from the game.
‘It’s a frustrating day, though, for him and everybody.
‘It was his first (league) game in something like 13 months.
‘So it’s a game he should take positives out of and try to build on going forward now.’
Jackett felt taking Whatmough off at the break was the right call to make, as he walked a tightrope against the pace Peterborough possess going forward.
He added: ‘He’s got a booking early on and I thought it was a yellow card.
‘I did think at half-time we needed to keep ourselves in it.
‘So I tried to change the dynamics and the flow of the game.
‘At half-time on a booking he wasn’t worth risking.
‘I did think after that booking and the nature of the second half, where we would have a lot of the play and then would threaten on the break it might be the right thing to do (take him off).’