For simplicity, let's focus on the elephant:
Elephants are Huge with a +20 to strength. African Elephant Anthropromorphic creatures are Large with a +12 to strength. If you decrease sizes, in this case, Huge to Large, according to Improving Monsters section of SRD, you would also get a -8 to strength. This would connect the +12 to strength for the large african elephant, compared to the huge elephant with a +20 to strength.
Due to the anthropromorphic's stat array, and the natural armor bonus, it would give a LA adjustment of +2. This information is found under Level Adjustment Examples on page 13 of Savage Species. However, their +2 LA is very conservative and it should probably be higher.
Whenever you look in the Monster Manual and see stats in a creatures description, in order to get the base stats, unless it directly says what its stats were, you subtract 10 from the number if it is even, or subtract 11 if it is odd. So, the elephant, having a strength of 30; you would subtract 10 from 30, which means it has a +20 to strength (at huge size). So if the DM wanted to create an Uber Elephant and give it a base strength score, of say 18, you would then add 20, and it would have a score of 38.
Now, many creatures also have higher stats according to their size increases. For example, whenever you go from Large to Huge, you gain a +8 bonus to strength (according to the Improving Monsters section). Yes, there are other examples of when you don't, such as Expansion using psionics. But we are talking about monster manual entries here, not psions.
African Anthropomorphic = Large Size with +12 to strength.
Elephant = Huge Size with +20 strength.
African Anthropomorphic as Huge Size would gain an additional +8 to strength, which would bump it up to +20, just like its normal animal counterpart.
There is your connection. It is just as strong as any normal elephant would be at its size.