On 16 December 2010, it was announced that Isa had signed for Castleford on a 12-month contract, Castleford coach Terry Matterson referred to this signing as being similar to that of Rangi Chase
In 2012, Widnes fan, David Quayle created a Facebook page on Isa, stating that if Isa was to score; the Widnes fans would riot. Despite popularity on Facebook, no fans rioted when Isa scored his first (and second) Widnes try against Hull F.C. in a 42–16 win.
In 2013, Isa found a new position, that position of second row transformed him into one of the form players of the super league. On 16 May 2014, Isa was the 9th player in as many weeks to sign a new contract and stay with the Vikings. He signed a new two-year deal.[5][6]
On 29 September 2015, it was announced that Isa had signed a two-year contract with an option for a 3rd year with Wigan starting in 2016.[7]
In round 20 of the 2021 Super League season, Isa was sent to the sin bin and placed on report for another incident in Wigan's 26–2 loss against St Helens.[11]
Isa played 22 games for Wigan in the 2022 Super League season. Isa did not feature in the clubs 2022 Challenge Cup Final victory over Huddersfield.[12]