wrong Boland is and has always been the team reserve bowler.
You're very late to the party Baggers and, as always, very wrong.
There is no such thing as 'the team reserve bowler' for starters.
Incumbent: 'holder of an office or post'.
Now there are two things. Firstly, no Australian cricketer is a holder of an office or post - they are selected in the team for that particular game. When that game is over all 11 positions in the team are up for selection again.
However, if someone was selected for the team they could be seen as having incumbency for that position. Boland was selected for the team. Therefore he was the Incumbent for the next team.
I would have thought that a supposedly cerebral chap like yourself would know these things.