Pros do not have access to all changes incoming to Dota 2. Frequently they can and will be blindsided by changes. If something is outrageously broken he will typically get ask pros for their opinions but the bulk of major content patches are relatively new to even pros. What IceFrog has is a group of private testers he has used for years that he can trust.

Here is the big difference here. The Dota 2 Community is used to major patches change significant portions of the gameplay mechanics.

With that said, IceFrog does exactly what people are pissed off about right now. He makes MAJOR changes to the competitive scene that can easily hurt teams that cannot adapt to changes. He also is not the kind of person who is immune to making horrible changes to Dota 2. Look at the Gold/EXP Kill Bounty system he introduced last year that meant if a team lost a fight they would almost instantly throw away their lead. He had to do some massive changes to it over a week or two period and even still today he is tweaking it.

He has even added heroes that are insanely broken and Valve/Him didn't nerf them until the community has had their go at it to see where the heroes are broken. Sure, he communicates with pros on these situations which is great. However, it doesn't mean these changes don't make it to the main client.

Now here is where CSGO and Dota 2 diverge. Dota 2 has a thing where heroes can be prevented from being used in Captain Modes so if they need additional tweaking or playtime they sit out. The other is the Dota 2 Test Client, that we don't have currently but will probably make a return. Although the test client is primarily there to test bugs for the upcoming patch. It's not there to test balances and tweaks. Big changes are usually pushed to the main client so the majority can test it and they can collect their data.