Vaczi, et al 2013 wanted to know what measures plyos improve for soccer players. They split a team into control and experimental groups. Both groups participated in soccer training. The plyo group participated single and double leg jumps three times a week.
The outcomes measures used pre and post the 6 week intervention were the T-Sprint test, the Illinois Agility test, Vertical Jump test and Max Voluntary Torque of the knee extensors.
The vertical jump improved 9%, T-Sprint improved 2.5% and Illinois test improved 1.7% and the knee extensor strength improved 7%.
Again, plyometerics demonstrate that with very short concentrated training, great improvements in strength, power, speed and agility are possible.