Chance of winning the cup is just the chance of beating each team multiplied. Leaving aside home/away issue, if we play three teams of exactly equal quality to us then our chance of lifting the cup is 7-1. If we played teams we are twice as likely to beat as lose to (ie teams that would be 2-1 to beat us) then our odds of winning improve to between 5-2 and 9-4.
Say you throw Celtic in with two roughly hibs-standard teams and assume Celtic are 1-3 to beat us, we're about 15-1 to win the cup. If it's two teams that are 2-1 against us plus Celtic then it's more like 7 or 8-1. So it makes a big difference.
We want to face the easiest teams - which seems obvious, I know - but this stuff about 'no easy games' and 'having to beat' people on the way etc isn't really right.