In my opinion, these bonuses are inherently flawed, and reward lack of play over dedication and hard work.
On one hand, you have an alliance that plays consistently, building up a lead with effort and hard work, often against a similar sized opposition over a number of days or weeks. Only to have that lead overturned by another alliance overnight because they come online in huge numbers simultaneously, but only for very short periods of time. They benefit from a x5 bonus to their scoring and end up demoralising and overtaking the alliance who has put time and effort into building up a lead. It takes a lot more numbers to take a keep than to defend it.
Why not remove the bonuses as soon as an underpopulated alliance has taken more than 50% of the map? They are obviously in control at that point and should no longer be considered an underdog.
Giving an underdog bonus up to taking the lead is simply unfair and discourages dedicated PvP play.
Where are all the Oranges? Plenty of other fruits in tamriel... Where are the Oranges??