Sanspo has posted a report that discusses how things might change (specifically with regards to the very real possibility that OF's will have to make more plays) this year with the addition of the new Mizuno baseball.
The report also notes that this isn't the first time Mizuno manufactured a baseball with less carry: in 2005, 10 clubs were under contract with Mizuno when they came out with a baseball with less bounce. The 12 teams of the NPB produced 1,747 that year. That's a drop of 247 home runs from the previous season (1,994).
The report continues by taking the Yomiuri Giants as an example:
The new regulation baseball travels a distance of 109.4m (a drop from 110.4m) under the following conditions: fastball velocity of 144km/h; bat speed velocity of 126km/h; and swing angle of 27 degrees. The distance to left-center and right-center at Tokyo Dome are listed as 110m.
In 2005, the Giants hit a total 186 home runs. The year before that, they banged out 255.