I thought he looked confident and assured at fullback, more so than Makinson.
I thought he took his trys well, and returned the ball well at fullback, taking some excellent catches.
I can think of two takes in particular which showed excellent hands. One was were he took a kick with both hands outstretched above his head, and the other was were he picked up a low kick from his bootlaces.
In the second half he came in for some stick when Saints fell behind because as usual some fans needed someone to blame. As a result when two passes he threw went in touch he was deemed by some in the crowd to be the cause of all Saints problems. Personally i thought he, along with other players kept missing Meli out because they knew Francis was injured and barely able to run.
He coped some stick of some people for the kick through, even though the kick was on the last tackle, we had nobody on the pitch able to put in a kick, and the kick itself was actually good and pinned Cas on their 10 yard line. Neither was there any clear overlap and try scoring opportunity.
The try that was conceded was IMO the fault of golden boy Foster and Meli ,who failed to tackle the Castleford player. Why the fullback should be blamed for failing to stop this try is beyond me, as they will be behind the line looking for kicks.
All in all a pretty decent performance on which to build. I would like to see Armstrong play more at Fullback as i think his size and pace would potentially cause teams problems.