Ryan Howard was in a slump and was overshadowed by teammate Chase Utley through April. His .168 BA, 5 HR, 12 RBI and 37 SO's for the month drove down his key rookie card values. His 03 Bowman's Best Auto RC went from a monthly average of $277.58 TAC in March to $221.76 in April. It then rebounded in May to $255.70, as he hit .238, 10 HR & 30 RBI that month, despite striking out 40 times. So far in June, he's been pretty stagnant, and his BB Auto RC has been dropping in value again, with an average of $196.12. Once Howard learns to reduce his strikeouts, we should see his BA increase and he should be able to regain his hobby-star status. When that day comes, expect his BB Auto RC to rise back up to the $300-400 range.
With Albert Pujols on the DL, opportunity should come-a-knocking for Rick Ankiel to step up and help the Cards maintain their NL Wild Card lead (or even compete with the Cubs for the NL Central). Ankiel's 99 Ultimate Victory RC was hot in April, averaging $37.04 TAC, as he hit .290 with 5 HR & 16 RBI for the month. In the next month-and-half, he saw fewer at-bats and only added 5 more HR & 14 more RBI, as his BA dropped to it's current .254. His UV RC has been selling in the $13-18 TAC range over the past week; a steal if he starts to heat up again. His most popular Auto, his 00 SPx Auto #'d 1500, has been selling in the $60's range over the past couple of months. I expect this card to also sell at reduced levels this month.
Ken Griffey Jr. hit his 600th career HR this month, but you wouldn't know it based on his rookie card values. His 89 Upper Deck RC averaged $31.11 in April and $26.89 in May. Since his historic swat on 6/9, this card has averaged $28.14. Griffey may have already reached his full hobby potential. Collectors probably shouldn't buy his rookies for investments (unless maybe his graded versions might hold more future value). I personally plan to hold on to my mint 9 specimen for my private collection.