How?
Not really a fan of Iwobi, but he does have pace and power and perhaps a more direct route about him, where as Bernard is more skillfull. Bernard doesn't have that power.
Had we expected a game where we would have 60% possession in good field positions, Bernard should be in. He has the intelligence, finds space, quick feet and thinking. We clearly set up at Watford to counter attack with raw pace and power. Which was what saw the winner, so I can completely understand not having Bernard from the start.
Even if i love the guy, some games require different things - which for me is the reason why there is no such tihng as a club having a 'strongest 11'.