Actually Wallerrrr, on average, velocity only increases by about a 1/2 mile per hour (usually no more than 1 mph) from Spring Training into the season.
However, 90 mph should be enough for Hanson if he can utilize his pitch mix which has a variety of speeds to keep hitter's off balance. His pitches have speeds ranging from the low 70's (Curve), to the low 80's (Slider and Change), to the high 80's/low 90's (Fastball) when running right. Somewhat similar to some of Jered's velocities except that Weaver is exceptional at precision control and maintaining his arm slot (hitting the corners and fooling the batters).