So, Acetyl-CoA (a 2 carbon molecule attached to Co-enzyme A) is the form in which the carbons enter the Krebs Cycle. Oxaloacetate is a Krebs cycle intermediate and is produced elsewhere in the cell via anaplerotic reactions (reactions that generate metabolic intermediates), so it's a bit misleading to state that it is the entry molecule. Also, the Krebs cycle itself does not produce much energy at all. 1 net ATP from the cycle is nothing. What it does produce are the reducing agents (NADH and FADH2) which carry the electrons captured from your initial Pyruvate (which was turned into Acetyl-CoA) to the Electron Transport Chain, which is the portion of oxidative metabolism that is the most important, and entirely overlooked here.
I understand you are probably going for a very simplified look at the process, but you are leaving out the most crucial portion of the process. Also, the products of the Krebs cycle continue down the catabolic pathway in order to generate ATP, the only products that don't are the 1 ATP (which is actually generated as GTP) and two CO2's.