A lot of local Gosusheep drug lords weighing in but where are the sheep tag professors?
What does removing the pen achieve? How is gameplay improved? What is the goal?
I haven't played this map but this this sort of setup creates a gameplay where wolves are forced to purchase a golem (or its equivalent), place it on the dead sheep, and have it hold position until the end of time. Wolves are in effect punished for kills: "Great job Turbo12, now stay there until you can spend all your gold on a golem." This removes skill/mastery across several verticals.
Secondly - if the map is even remotely similar to WC3 Sheep Tag - you should be aiming for a sheep win rate of far below 10% given equivalent parameters (i.e., 20 minute time limit). Should go without saying and if not I'd strongly suggest trying out the WC3 version.