“Same tactic got Linseed Graham re-re-elected last year.”
Yup.
Actually, that's not what happened. The large field is what gave any chance at all to keep Lindsey under 50% in the primary, thus forcing a run-off. In a run-off, it would have been one against one. The thing that got Lindsey re-elected was A: he had a huge advantage inherently as a long time powerful incumbent and B: Graham wisely used that advantage and early on he made deals with would be supporters not to run and not to support anyone who does (Gowdy for example) and C: the only one remaining with the chops was Lee Bright, but he had other obstacles that were very problematic.
As it turned out, Lee trounced the field for second place, even as he had a much smaller budget than all the others, but Graham came in comfortably at 56%.