He knows what they're saying about him upstairs at Wrigley Field, not to mention at the Cubby Bear and Murphy's Bleachers. He knows he's no longer seen as a candidate to take over center field for the Cubs, not this spring anyway. Brett Jackson understands, and it's water off a duck's back. "I'm aware of comments they've made,'' Jackson said Sunday, referring to his having a reserved spot in the Iowa lineup. "That's fine. That doesn't detract from me playing the way I want to play. I'm going to play like I deserve to be on the team … I'm going to do everything in my power to be on this team.'' Jackson can wait a little longer to get back to the big leagues, if he has to. What he can't do is fail to hit the ball when he gets there, as was the case in September. "One of the reasons he was there was for us to get a good look at him, see how he would do against big-league pitching,'' Cubs manager Dale Sveum said. "Well, there were some important adjustments (he) had to make. He has done a good job (adjusting).'' Not that long ago, the 24-year-old Jackson was widely considered the best prospect in the Cubs organization. He's a Jim Edmonds starter kit, but these days he's more often mentioned with baseball's most strikeout-prone hitters, guys like Adam Dunn and Mark Reynolds. Jackson finally had enough after his whiffing 217 times last year, including 59 in 142 at-bats after receiving a late-season promotion from Triple-A Iowa. If he was ever going to be open to a suggestion that he overhaul his swing, this was it. He played in 44 games for the Cubs, including 31 of the 101 losses. The hole he dug just got deeper and deeper as he hit .116 with one extra-base hit in his last 20 games. After a month off to clear his head, the left-handed-hitting Jackson met with Sveum and hitting coach James Rowson in Arizona. They worked to lower his left elbow — effectively dropping his hands and leaving less room for the bat to travel to the ball — and on other ways to shorten his swing. They also worked hard to rebuild his confidence.