My assistant pointed me to this thread after he got a notification of my name via Google alerts. Couldn't resist...
Simple, yet easy way to handle this is to go to the research.
Derenne C, Ho KW, Murphy JC. Effects of general, special, and specific resistance training on throwing velocity in baseball: a brief review. J Strength Cond Res. 2001 Feb;15(1):148-56.
Specific studies they referenced:
Bagonzi, J.A. The effects of graded weighted baseballs, free weight training, and simulative isometric exercise on the velocity of a thrown baseball. Master's thesis, Indiana University. 1978.
Brose, D.E., and D.L. Hanson. Effects of overload training on velocity and accuracy of throwing. Res. Q. 38:528–533. 1967.
Jackson, J.B. The effects of weight training on the velocity of a thrown baseball. Master's thesis, Central Michigan University,. 1994.
Lachowetz, T., J. Evon, and J. Pastiglione. The effects of an upper-body strength program on intercollegiate baseball throwing velocity. J. Strength Cond. Res. 12:116–119. 1998.
Logan, G.A., W.C. McKinney, and W. Rowe. Effect of resistance through a throwing range of motion on the velocity of a baseball. Percept. Motor Skills. 25:55–58. 1966.
Newton, R.U., and K.P. McEvoy. Baseball throwing velocity: A comparison of medicine ball training and weight training. J. Strength Cond. Res. 8:198–203. 1994.
Potteiger, J.A., H.N. Williford, D.L. Blessing, and J. Smidt. Effect of two training methods on improving baseball performance variables. J. Appl. Sport Sci. Res. 6:2–6. 1992.
Sullivan, J.W. The effects of three experimental training factors upon baseball throwing velocity and selected strength measures. Doctoral dissertation, Indiana University,. 1970.
Swangard, T.M. The effect of isotonic weight training programs on the development of bat swinging, throwing, and running ability of college baseball players. Master's thesis, University of Oregon,. 1965.
Thompson, C.W., and E.T. Martin. Weight training and baseball throwing speed. J. Assoc. Phys. Mental Rehabil. 19:194–196. 1965.
They also have a table that summarizes 26 studies that examined the effect of different strength protocols on throwing velocity, and 22 of the 26 showed increases over controls who just threw.
The saddest part is that the training programs they outlined were crap - lots of 3x10 with light dumbbells and therabands. If archaic stuff like this works, just imagine what good S&C can do.