Tinker + Ursa

Why this works

Fighting over the same farm on the map makes it difficult for this pair to succeed. Tinker needs to occupy multiple lanes and jungle areas to accelerate with Rearm, while Ursa relies on securing his own section of the jungle and early Roshan attempts to hit his timings. This competition for resources means one or both heroes will inevitably be behind schedule. Mechanically, their kits don't mesh well. Tinker provides no hard lockdown to help Ursa close the gap, and Ursa's Enrage-fueled rampage offers no way to peel for a Tinker who gets caught out of position.

This leaves the team feeling fractured. Ursa will want to group up and force fights around his key item timings, but Tinker is often on the opposite side of the map, applying pressure and unable to contribute meaningfully to a brawl. This split focus allows opponents to isolate one hero or the other, taking advantageous fights and securing objectives. The core problem is that both heroes want to play their own game, and the enemy team can punish the fact that those two games rarely overlap in the same place.