The only way you are making sense is if each of the teams has deploy points on ONLY ONE node. If team 1 scores 300k deploy points on one node and team 2 scores 270k on a separate node then highest deploy points are highest control points. However, that is not usually the case. Generally team 1 deploys over several nodes as does team 2.
If you lose a node your team still gets your own deploy points. If you win a node, you get your teams deploy points PLUS the points deployed by the other team (s). Thus your teams points plus that deployed by other team = control points.
What you are missing is that BOTH TEAMS get the deploy points that are calculated into control points. The deploy points don't get subtracted from the team who lost the node.
Team 1 deploys 300k. Team 2 deploys 270k. Say over two nodes. But team 1 tried to steal (or had players who couldn't follow directions) a node and deployed 20k on the node team 2 eventually won. Team 1 still gets 300k deploy points but only 280 count for control points. Team 2 gets 270k deploy points but 290 count for control points. Thus team 2 is winning the war with fewer deploys.
See?