The Missing Heroes

Here is the list of heroes that haven't been picked in the main event so far for TI5*:
abadon
alchemist
batrider
beastmaster
brewmaster
centaur warrunner
chaos knight
death prophet
doom
drow
elder titan
entrantress
enigma
faceless void void
huskar
invoker
kunkka
leshrac
lich
lifestealer
lone druid
medusa
meepo
mirana
morphling
necrophos
nyx assassin
ogre magi
omniknight
oracle
outworld devourer
phanrom assassin
puck
riki
shadow demon
slardar
slark
techies
terrorblade
tidehunter
tinker
tiny
teant protector
troll warlord
ursa
vengeful spirit
venomancer
visage
warlock
windranger

Of these, the ones that have a strike through were banned at some point during the main event (there may be more but these were the most significant.

Most of the rest have been hit with with the nerf stick recently, don't fit in the meta, or are just too risky to pick. Here are a few heroes that I feel could be picked, whether situationally or otherwise.

Brewmaster - this hero used to be first pick/ban material. He's fallen out of favor recently but the hero is potent in team centric and push centric line ups. You need to use split, get a kill or two, and take an objective.

Centaur Warrunner - this hero can be a monster in the offlane and was picked up in the group stages 6 times. While he didn't have a great showing, he is similar to tusk, but offers a global presence with his ultimate. He does need a blink dagger to start initiating on people, however his damage output, tankiness and an ultimate which is always useful means that he stays relevant all game.

Enigma - many teams play this hero, but he's greedy. And Rubik is running around wrecking teams. (Just watch Fy God destroy Empire singlehandedly twice and you know why enigma is super risky.

Enchantress - we might see this in the offlane for EG or jungle for Secret nut otherwise this is a risky pick. Still, capturing the early game with kills seems to be a good way to win, especially shutting down the mid. A Darktroll Summoner, Centaur, Hellbear, or Golem can secure kills. Also, a Wildwing can be super annoying or guarantee fast farm with stacks.

Lich - this hero dominates in the dual-lane meta. His abilities lend themselves to winning lanes which seem to be a key to victory.

Puck - this hero has always been good and the aghs upgrade keeps him relevant against bkb as the game progresses. Dream Coil comes online when the Undying Tombstone is at it's most powerful (level 3-4) and the silence is extremely relevant against many of the mids currently being play.

Slardar - Slardar tears through carries that need more time to come online and, with a blink dagger, can catch out many heroes with a near instant stun. This hero also naturally builds items to help push. The other two important aspects which are important to consider are granting an early Roshan and grants information through amplify damage. In an aggressive line-up, this hero excels; get kills, take objectives.

Tidehunter - We might see this on Iceiceice or Universe, but he's MIA. It's unfortunate but the offlane choices right now are not favoring the thing from the depths.

Tiny - we might see a tiny wisp before the event is out, but right now he's being completely ignorged.

Ursa - another aggressive carry that is seeing no love. He's been buffed and retooled since the last TI and now he's even stronger. Like Slardar, Ursa offers an early Roshan. While Ursa doesn't have the lock-down that Slardar offers, his burst damage tears through anyone who can't get away like SF, Clockwork, Lina, and supports who don't have a disable.

*the list is aailable at the bottom of the www.dotabuff.com/esports/events/41/heroes page