I would say salary cap for foreign players in BPL is pretty low, in order to attract more players this should be increased. I guess its still not bad for only few weeks of play. Baseball players usually makes hell lot more money just by chewing gum in the bench.
A-->$70,000 USD
B-->$50,000 USD
C-->$40,000 USD
D--->$30,000 USD
Baseball's wage structure is totally different - it's the most polarized salary structure in any pro sports, because there is no upper or lower cap.
Baseball franchises (MLB, can't say about Nippon League, rest are not even mentionable) maintain one of the largest roster in any major sports - over 35 players. One main reason being 162 matches in 180 days, just in regular season. But, there are handful of players that are paid crazy - rest are surprisingly low.
For example, at Jayes, Donaldson, Bautista & Russel Martin are paid over $60mn US combined/season, but Piller has $800K contract for 5 years - it might happen, next time Kevin Piller increases his wage by several times, but his current contract is like an EVP of a bank.
For a direct comparison - both Liverpool & Boston Red Sox are owned by FSG. LFC has around 25 listed senior players, while Sox around 35. Last year, David Price & Ortriz were paid $75mn US in total (40mn +35mn), while LFC's highest earner was Coutinho (£150k/Week ~£8mn/season ~$12mn US), while Klopp is paid around £221,000/week.
Still, LFC's total wage expense including bonus, office staff & support unit was around $213mn US (this is excluding transfer fee, agents' commission, medical fees & players' life insurance). Same time, for almost twice the people under wage, Red Sox's wage expense was less than $200mn; and in baseball there is no Transfer fee & very little agent commission (agents are paid by players, rest others are similar). Remarkably, Real Madrid & NY Yankees has similar wage expense - this is because in club football, the wage disparity is not that much like baseball.
I think, best wage structure in sports still is NBA (highest cap $27mn, lowest for 1st team is around $2.5mn) & football (Bundes Legua - probably Lewandwiski is highest paid at Bayern for 250K/week, while they have a minimum wage cap for the listed starting 25 players at the start of the season, which is 35k/week).
BPL salary is fine - at least if it can keep few fast bowlers left in the game protected. Instead of paying higher, I'll solve the entertainment issue other way - bring boundaries to 45 metre, every team 'll have few Richards; allow fixing - every match'll end on last ball thriller; put a mat on half volley length - 3 balls in every over has to drop there .... otherwise double free hit...... what every match, every ball will be dhamaka.