KOTOR disagrees with you.
Revan was largely responsible for the Republic success in that war for many reasons.
Let me break down Revan's success for you, and those who think the same as you do.
The Republic was crumbling, the Mandalorians were destroying the Republic military and morale was low. Suddenly, an army of Jedi takes command of the Republic fleet. Morale skyrockets and the Republic begins to recruit a vast number of troops. The Republic's numbers grow exponentially, greatly outnumbering the Mandalorians with the aid of the Jedi.
Command of the fleet is given to Revan, Alek, Meetra Surik, Saul Karath, Kavar, and others. Revan decides upon an aggressive course of action, leaving worlds undefended to make a strike against the Mandalorians. The fleets led by Meetra, Kavar, and Alek secure countless victories and pushed the Mandalorians to the borders of Known Space.
Revan did not win the war alone. If not for his allies, the Mandalorians would have pushed them back. What we can say for Revan is that he was able to rally the Jedi to join the war.
Revan could have easily turned Mandalore's false war strategy against him and strung his forces along in the same way the Mandalorians had done. This would not have only saved lives, but would have brought an easy end to the war. Instead, Revan chose an aggressive tactic (the Mandalorian's tactics) that costed more lives than any other strategy would have.
The reason I say Revan is not a tactical genius is because if he were a genius, he could have easily turned the war around through his own tactics. His use of Mandalorian tactics would have failed if he didn't have the Jedi numbers he had.