Would MacArthur have lost Guadalcanal?

Would the Guadalcanal campaign have been lost if Douglas MacArthur controlled the theater?

Probably not, though the campaign might have taken longer under his command.

A Japanese victory remains unlikely in this brief counterfactual. MacArthur's command style might add delay and more attention to presentation, but American material advantages would remain. The campaign would probably take longer without being lost. The concise reply does not reconstruct the theater command arrangement in detail.