Personally, I've come to believe that instead of retiring numbers, the numbers should be assigned anew each season in a special ceremony at Spring Training. Once the starting players for all the position players are determined, they are assigned a number that corresponds to the position's scorecard number (2 for catcher, 3 for first base, and so on). Now the #1 is the pitchers number but since you have multiple pitchers, the starting pitchers numbers start with one so your ace wears 11, your number two pitcher wears 12, and so on. Bench players wear numbers in the 20s. If you have a platoon you might want to assign both players a number in the 20s instead of giving one of them a number in the 2 to 8 range. The bullpen wear numbers in the 30s. Players acquired in-season through call-ups or trades get numbers starting from 40 in the order that they arrive. If you have a player who is exclusively a designated hitter, they wear 0. I would reserve the #1 as a special honor that can be awarded to a pitcher if they won the Cy Young Award in the previous season or some similar accomplishment like leading the league in ERA or strikeouts. Similarly, the #10 would only be given out to a position player who accomplished something great in the previous season like winning the MVP or leading the league in homeruns. Anyhow, that's my system.