An MVM map I had an inspiration for
Fix your imgur links to make all images show, now we only get the first. I gave the correct urls with my comments:
http://imgur.com/RAf0i1N
A deathpit this close to spawn can make it very easy to delay a map into a very long state. In none of the valve maps there is a deathpit this close that is easy to use. Rottenburg has it hidden quite far in the back, and coaltown has it a bit higher meaning once its in the pit its harder to get it out.
http://imgur.com/wsdYEE0
I cant see what this image is trying to show. it just shows a rough blocking area of a defense position, but it doesnt show its usability
http://imgur.com/jo6NLHk
Although the path seems clear its a bit dull to me. Its a straight rectangle path, i would try to put some objects in to force a little zigzag behaviour. Alternatively a simple slope as path itself is also capable of providing some change as in that case you get some changes in the vertical aiming.
http://imgur.com/EeMBIj5
This at least is a good screenshot to show how a defense area is ment. but again its still just a few rough blocks.
For an mvm map its quite vital to set the detail shapes quite early. These are going to provide key parts into the defense. A straight path in early playtests might not provide them building defenses, but as soon as there is 1 crate they suddenly might use it as a primary place. The strongest defense position is what people take, try to create and find these as early as possible and base the map around those.
Also, your map doesnt seem to show alot of spine's. These are blocks at more central places which are often used as a place to safely build a teleporter and at lower levels build the sentry nest. Without spines a map will become hard to defend as there are no good spots to start on. And the only option you would have is running.
And last, with mvm maps which are ment to get a shape ready. provide an overview with arrows of the bot paths. thats the best mvm indication you can have.