For me “turning point” means when Japan lost its momentum to launch attacks and past the point where they had any hope of winning the war. Though midway certainly slowed Japan down significantly they still had like three carriers by 1942. After the battle of Santa Cruz America had one heavily damaged Enterprise up against Japan’s 3 fleet carriers, and after Savo Island we had to pull out all our cargo ships attacking Guadalcanal and left the marines to fend for themselves for months before they were reinforced. Through most of the Guadalcanal campaign Japan had logistical superiority and had the means and resources to supply and arm men putting 35,000 men into the islands. By this time Japan was still quite capable of matching America in in terms of ships and manpower but after the 6 month Guadalcanal campaign Japan had lost most of its experienced air crews and more importantly, America held off Japan for their industry to be capable of outmatching Japan. If Japan had better soldiers and tactics and had won Guadalcanal the war would have continued for much longer and would have been far from defeated and the war would have dragged on.
Bottom line US doesn’t achieve an uncontested superiority over the Japanese in production and ships until after they defeated Japan at Guadalcanal because they kept loosing carriers in the battles of Coral Sea, Midway and Santa Cruz and did not replace these losses until after the battle.
