I can’t speak from the baseball side, but the best stats on Superman would arguably be from the DC Heroes RPG. Here are relevant stats for various incarnations of Superman, along with what they translate to. The stats generally translate to a range - I’ll use the upper limit to the ranges. Others can use these benchmarks to figure out what it means for baseball. The standard way of determining how far you can throw involves the STR stat, but I’ve included other stats that might be relevant for calculatiions based on Superman’s other attributes and powers.
Superman (2nd edition DC Heroes with Mayfair Exponential Game System)
1938
DEX 10 / STR 15 / Superspeed none / Flight none - Jumping 12
1942
DEX 7 / STR 13 / Superspeed 13 / Flight 12
Pre Crisis
DEX 26 / STR 50 / Superspeed 25 / Flight 45
Post Crisis
DEX 15 / STR 20 / Superspeed 14 / Flight 15
Post Byrne
DEX 15 / STR 25 / Superspeed 11 / Flight 18
DEX determines basic movement speed
10 = 900 miles/hour
7 = 112.5 miles/hour
26 = 57,600,000 miles/hour
15 = 27,000 miles/hour
STR determines how far you can lift or throw an object (in this case up to 50 lbs)
15 = lift 450 tons / throw 50lbs 30 miles
13 = lift 110 tons / throw 8 miles
50 = lift 1.63x10^13 tons / throw 1.07x10^12 miles
20 = lift 15,200 tons / throw 1000 miles
25 = lift 486,400 tons / throw 32,000 miles
The system is only set up officially for 0-50 lbs. But assuming a baseball is 142 grams (.31 lbs) and extrapolating the rules system, theoretically this would make throwing it:
15 = throw baseball 2000 miles
13 = 500 miles
50 = 4,194,304,000 miles
20 = 64,000 miles
25 = 2,048,000 miles
Jumping
12 = jump 4 miles
Superspeed
(in this case up to 50 lbs)
13 = run/throw 50lbs 7200 mph or throw 8 miles
25 = run/throw 28,800,000 mph or throw 32,000 miles
14 = run/throw 14,400 mph or throw 16 miles
11 =run/throw 1800 mph or throw 2 miles
(extrapolating for baseball)
13 = throw baseball 450,000 mph or 500 miles
25 = 1,843,200,000 mph or 2,048,000 miles
14 = 900,000 mph or 1000 miles
11 =112,500 mph or 125 miles
Flight
12 = 3600 mph
45 = 3.02 x10^13 mph
15 = 27,000 mph
18 = 225,000 mph