Well, their team only had one tank: Voli. You guys had a WW on your team so that's basically a one for one on the tank factor. Their team wasn't building resistances but neither was your team (besides WW). Your team had 3 clarity summoners which is a big no-no. I get mad when there is more than one on the team. It restores 40% mana for all nearby allies, so having 3 is complete overkill. Take an exhaust and an ignite on your team as it can shut down regen/healing champs like Voli and WW and lower the damage of an incoming assassin or other high damage dealer. It can also help secure a first blood. Now, your team had no CC. This is a problem in itself. You can not lockdown targets with your team comp without WW.
The opposing team had plenty of CC and a Brand. Brand is in my opinion, one of the most abusive champions in ARAM. His damage is insanely high, he has a very strong stun and his Ult can destroy grouped up teams in the Howling Abyss. Sona is no slouch either. She has a very spammable heal and her powerchord + lichbane can chunk any squishy target. You guys had a tough matchup, so don't let it get you down too much.
Since you were running a very dive heavy assassin type team, you should look at your weaknesses and your strengths. You had a very dive in team especially at level 6. You could have coordinated with your team to go in as soon as WW picked off a target, preferably not Volibear. The only offensive person on your team that wouldn't be able to get out after diving in is Master Yi. He has to hope his W can keep him alive. Talon can use his Ult to escape after blinking in and Nidalee can jump in and out of fights in cougar form. You can use a very hit and run style, but keep in mind that you must win the fights you pick. Even if you go even, the other team can heal up with Sona. You have Soraka on your team so have her use her Ult when you dive in. She can heal you with her W, but it costs her own health so don't let her get down to 5% HP or she'll just die to a Sona Q.
Itemization. You seem to want to complete your items very quickly before starting another item. This seems like a good idea to get the passives of the items quickly, but champions like Talon are strong with just pure stats. Black Cleaver is a big commitment as its combine cost is over 1200 gold. Additionally, its passive is not as useful in the early game as it is in the late game. Keep the Brutalizer for a while before upgrading it. Keeping Mid Tier items in your inventory can be better for you in the early to midgame with champions like Talon, Pantheon, and Xin Xiao. My build with Pantheon on ARAM usually looks something like this 
before I start completing items. Talon can work with a similar build style, so I suggest trying it out. Another thing to always consider when facing a team with Ahri, Brand, and Sona is that an Aegis can do wonders for your team. Ask WW or Soraka to pick one up in this situation.
Finally, it does look like your Nidalee was having trouble that game. She probably thought that she should just sit back and chuck spears for the whole match and come out on top due to Nidalee's high damage from that ability. But when facing a sustain comp, poke doesn't win out (unless you can put out more poke than they can heal 
). You have to take down the opponent before they can heal back up, so in this situation, going in and trying to take the enemy out quickly is your best bet. Don't let it get you down though, sometimes you just face a hard matchup. Good luck in the future. It's just ARAM, so have fun.
