This is wrong.
Read
the article I linked. P-39s arrived in Russia in Dec 41 / Jan 42. They went through a 3-4 month workup up until April of 42, and this extended workup almost certainly contributed to the success these units had with the type. By June 1942 the P-39 "cobra" as the Russians called it was deployed in large numbers on the front and had a high success rate. As a fighter with good armor, working radios, and arguably as fast or faster at low altitude than all the existing fighters on the front on both sides, at least at combat altitudes they were fighting in, it was a major shot in the arm for them. I'm not sure precisely how many they had in combat in 1942, but even ~ 600 planes on the front, if they were considerably better than the I-16s, MiG-3, LaGG-3 and early Yak-1 and Yak 7 types that made up the vast bulk of Soviet fighter forces, was a major help.
Note for example the 28 GIAP, active from 30 June 1942 until Sept 1942. With 20 P-39s, they claimed 64 enemy aircraft for 8 aircraft and 3 pilots lost. Even if you don't believe their claims (which were backed up by identity planes from the crashed aircraft, with aircraft crashing inside German lines not counted) the very low loss rate for this period in the VVS in three months of fighting stands out like a sore thumb - many other Soviet fighter squadrons were 'reduced' to non-flying status in just 2 or 3 weeks in the same period.
They also had substantial numbers of Hurricanes and a substantial number of Tomahawks in 1942, but they did not have as much success with these. Both Hurricanes and Tomahawks shipped to Russia were often battle weary machines already used in combat in the Middle East or elsewhere, with 'clapped out' airframes and engines. They had a lot of problems adapting the aircraft and engines to the field conditions in Russia, particularly Winter conditions, and the Russians themselves have said that in particular they did not like the Hurricanes as combat aircraft. The Tomahawks and Kittyhawks were better but suffered badly from mechanical problems especially burnt out engines, so they were only useful for a short time.
That said, you are correct to point out they got a lot of Hurricanes and they were in use in front line squadrons, notably up in Finland for example, and the Soviets did have some Hurricane Aces. They may not have been as bad as they said they were.
There were many more P-39s in 1943 but by then the Soviets had their own capable planes in large numbers: the Yak-1B, Yak-9, and La 5 and 5FN. Those few Lend Lease planes they had in 1942 were almost certainly more critical to the war effort.
A few stats on deliveries from here:
Aircraft Deliveries
quote:
"In addition to the aircraft deliveries American Lend-lease deliveries to Russia included also more than 400.000 trucks, over 12.000 tanks and other combat vehicles, 32.000 motorcycles, 13.000 locomotives and railway cars, 8.000 anti-aircraft cannons and machine-guns, 135.000 submachine guns, 300.000 tons of explosives, 40.000 field radios, some 400 radar systems, 400.000 metal cutting machine tools, several million tons of foodstuff, steel, other metals, oil and gasoline, chemicals etc. "
and also:
"Some American aircraft types were simply irreplaceable and very highly appreciated on all levels during the war, e.g.
P-39 Airacobra fighters, A-20 Boston and B-25 Mitchell bombers and C-47 transport aircraft."