Ive been drafting battlecups since they began and i have been unable to find any mid level drafting advice for this purpose. Im usually up to date with the meta and attempt to identify why pros pick certain strategies/heroes and then proceed to build a team with these concepts in mind, however with the skill caps of my team mates in mind.
As a little background I am legend 4, and the reason for this I am just not that mechanically good. I've won 3 tier 3, 2 tier 4, 8 tier 5 and 1 tier 6 battle cups in which i have drafted for at least in part.
For your pos 4 and 5 you'll want some intiation/disable and also some percentage based damage or damage amp. For the former some heroes include SK, Bane, Disrupter, Willow, Earth Shaker and the latter would be AA, Slardar, ET, Undying, Warlock. The ideal pairing of supports will allow you to win your lanes, have potential to gank as a duo, and structure your teamfights, usually you will want one of your supports to have wave clear also.
This lane is alot harder then it used to be. Beastmaster and doom seem to be ok to first pick for the pros but they need to be played around in a certain way which needs practice. So we're dropping them, you'll want to 3rd or 4th pick your offlane. You need something that wont get stomped. This is the main thing. Getting your offlane crushed is really bad right now. Think tanky heroes that can zone supports to farm or heroes that can use cheap spells to last hit. BM does both which is why hes so OP right now. Axe is great with another spammy support (disrupter/sky/IO), Underlord can work, undying is good for tri lanes, enigma will usually force the other team to dual lane if you just deny the ranged creep (although your probably better off just picking lich), tide is also a solid pick but low damage.
Zues is super good with AA, Undying or ET to amp up the damage, if he is in the pool take it 3rd if they dont have any pipe builders yet. Other then that keep viper/dk in mind if you need something to come online quick, DP allows you to group as a 4 if you plan on pick a split pusher carry. You should have a specialised mid player and they will have preferences, ask them what they want.
Usually you'll pick this last unless they pick their offlaner early. Someone who can hit buildings or split push is usually what you want, also keep in mind that rosh is hard to take right now. Troll is probably the best hero for doing all these things. PL is still good if they have mostly single target. If you go for a more teamfight oriented team I would suggest terroblade. Just be careful of picking Battle fury carries, you can easily lose too much map control if you go down that avenue.
Basically you want to take all enemy tier 1's (or at least the enemy safe lane and mid tower) by 20 mins. Switching your carry to the enemy jungle and warding it will allow them to farm half the map and pressure the tier 2. Usually this is when you swap your initiator to the safe lane to farm up a blink dagger. This is because the safelane becomes a death trap past 10 mins. Its way to easy to easy to dive and TP's can only come from 1 place, Getting the mid tower will allow you to rosh if you have the right heroes and you lanes are pushed out, or you've killed the enemy team fight specialist.
Whenever you teamfight, make sure you have vision, or at least keep a ward handy so you can put it down when the fight breaks out. This is more important then you can believe. Vision wins fights, its incredible how differently fights go with or without vision.
Bonus Tip - The easiest way to throw a 10k gold lead is the fight around the enemy offlane shrine area if its warded. If you really want to force a fight there, pop smoke go as a 5 and put a ward on one of the ward towers. The reason why its so bad is because the enemy has 4 points to TP in from and the trees and high ground obscure SO much vision, let alone the shrine itself. Just be very careful about engaging in that area.
These are some basic Draft templates that I've come up with based on what the points I've presented and others that i wont bore you with. The are ordered 5-1
Lich, Sandking, Undying, Zues, Terrorbalde.
Warlock, Sandking, Axe, Leshrack, Troll.
AA, Nyx, Underlord, SF, PL.
(you may want to dual lane mid for the first creep wave with AA SF)
Alot of teams are switching lanes to get better match ups, just keep in mind your win conditions and what your power spikes are (eg. sk blink, troll bkb) and facilitate those heroes. Another common trend is putting the pos 5 in the offlane eg. disrupter and have the pos 4 start in the safe lane. Another tip is to buy a ****load of regen on your offlane heroes. This includes your support, dont be greedy, and dont lose your lanes.
I plan on doing more of these in the future with less information and focusing more on meta and actual drafting.
Good luck and i hope that this gave you something to think about when you do your next draft.
Any criticism is welcome and remember to up vote if you think i should do more of these drafting type guides :)