A number will have benefitted Pompey financially, with offers for the likes of Matt Clarke, Marcus Harness and Jamal Lowe too good to turn down.
Others, though, will have raised a few eyebrows and left many supporters disappointed.
Indeed, there’s quite a few departures that make you wonder ‘what if?’ if more of an effort had been made to retain certain individuals.
Here are 18 former Pompey players we believe fit into that latter category since the Blues returned to League One in 2017.
9. Nathan Thompson
In 2019, Thompson left Fratton Park upon the expiry of his contract in search of Championship football. He made 77 appearances for the Blues following his free transfer arrival from Swindon in 2017. The defender returned to Pompey later that summer to maintain his fitness after initially failing to find a club. However, a permanent return was ruled out after the Blues had already signed James Bolton. Photo: Joe Pepler
10. Jack Whatmough
Despite then-boss Danny Cowley keen to retain the services of the centre-half, Pompey were unwilling to offer the out-of-contract Whatmough more than an initial 12-month deal. As a result, the defender ended his 13-year love affair with the Blues by signing for Wigan on a free transfer in 2021. Photo: Dennis Goodwin
11. Andy Cannon
The midfielder was the most high-profile name among the departures when the Blues announced their 2021 retained list. Cannon was a key player during the 2020-21 season, making 49 appearances as Pompey just missed out on the League One play-offs. The club did hold the option for an additional 12 months, which the ex-Rochdale ace and then head coach Danny Cowley discussed. However, with Cannon wanting to move back closer to home, it was agreed he'd leave the south coast. Photo: Jason Brown
12. Craig MacGillivray
The popular Scot amassed 135 appearances during his three campaigns at Pompey and was an ever-present in League One in 2020-21.That season also saw the keeper voted The News/Sports Mail’s Player of the Season. However, then-boss Cowley elected not to activate a club option to extend MacGillivray's expiring contract by an additional 12 months. Cowley told The News in the summer of 2021: ‘The option had a significant increase to what Craig was earning, so then you have to weigh it up. Ultimately, you can only value any player within your budget. That’s what you have to do.' Photo: Jason Brown