From my experience, during pro matches or high level matches, stacking HP is always better than stacking speed. Early game, you will stay longer on lane, keeping flag and farming same or more. Late game you'll be more efficient to chase or flee; but you will be inferior in every confrontation (except if opponent is hurted or 2v1).
With players of exactly same levels and skills, HP will always beat speed imo. But I'm sure it can be viable (and very enjoyable) in matches more "easy". That can explain:
I either have great success (9-2) or I epically fail (0-7).
The same way, you can perform very well with Reg or TB in most matches. But they'll be a handicap as soon as it's a pro match and there are 3 strong DG in front of you (Ere, Oak, UB for ex?)
Maybe the Reg in that match was a handicap for Orcun's team? (I am not saying eXborderline is not good, I just say Reg is weak in pro match...)