Finite simple groups of section 2 with rank at least 5 have Sylow 2-subgroups with a self-centralizing normal subgroup of rank at least 3, which implies that they have to be of either component type or of characteristic 2 type. Therefore, the Gorenstein–Harada theorem splits the problem of classifying finite simple groups into these two sub-cases.
References
^Gorenstein, D.; Harada, Koichiro (1973). "Finite groups of sectional 2-rank at most 4". In Gagen, Terrence; Hale, Mark P. Jr.; Shult, Ernest E. (eds.). Finite groups '72. Proceedings of the Gainesville Conference on Finite Groups, March 23-24, 1972. North-Holland Math. Studies. Vol. 7. Amsterdam: North-Holland. pp. 57–67. ISBN978-0-444-10451-9. MR0352243.