A number of pitchers with something to prove were in action in the Valley of the Sun on Monday, and I caught part of the Reds' morning "B" game against the Brewers, before catching the afternoon Angels/Rangers tilt, in order to see a few of them.• After two years in Japan, 30-year-old Colby Lewis has returned stateside, and I consider him a big AL sleeper for this season. He has returned to the same organization that drafted him, but also waived him in 2004 when he needed surgery for a torn rotator cuff. The shoulder surgery turned out to be a blessing in disguise for Lewis, who has emerged from two seasons with the Hiroshima Carp as a completely different -- and better -- pitcher, and one who likely will open the season in the Rangers' rotation.Lewis posted a 369-46 strikeout-to-walk ratio in 354 1/3 innings (54 starts) in Japan over the past two seasons, turning himself into a strike-thrower with a more compact, repeatable delivery that allows him to command the ball far better than the pitcher I last saw with Oakland in 2007. He also has added a good cutter to his repertoire. Put it all together and Lewis becomes a pitcher who could have a bigger impact for the Rangers this season than most people realize.He worked two innings Monday. He did allow a solo homer to Mike Napoli (a big bomb to center field on a hanging curve), but was otherwise impressive, throwing 20 of his 26 pitches for strikes, working very quickly and efficiently, and being aggressive. He reached 92 mph a few times and had very good cutting action, and also showed he could throw his fastball to both sides of the plate. He mixed in a curveball that ranged from 74-79 mph that was sharp at times, but a bit inconsistent. He also mixed in some good 82-83 mph sliders, and even ran it in the back door against a few lefty hitters. There was a lot to like, and it was hard to believe I was looking at the same pitcher I saw a few years ago. I snagged him for $4 in the AL LABR (League of Alternative Baseball Reality) auction Saturday, and was happy then to do so. I'm even happier after seeing him Monday.• Ervin Santana showed exactly what he needed to in pitching two sharp innings Monday: velocity on his fastball and snap on his slider. Both were missing for much of 2009 as he battled forearm and elbow injuries while posting a 5.03 ERA. However, those numbers are deceiving; as his health got better last season, he improved, posting a 2.48 ERA and two shutouts over his last 11 starts. Santana was throwing 93-94 mph Monday with an 81 mph slider that had good tilt, a very positive sign that he'll be in position to have a bounce-back year. Obviously, just because he's healthy now doesn't mean he'll stay that way, but his average draft position is No. 233 right now, meaning there's a good buying opportunity there. Start moving him up your draft boards.• Derek Holland tried to do too much too soon in his first appearance back from an early knee injury in camp, retiring just one batter Monday. Considering he's fighting to maintain his rotation spot from last season, he needs to get back up to speed fairly quickly. Holland hit 92 mph consistently with his fastball but struggled mightily to locate. To be fair, he was not helped by some poor defense behind him, but his low-80s slider also was a bit flat, and he mixed in one curve.I'm a believer that Holland can take a big step forward this season, and he's definitely one of my sleepers. However, he needs to have a starting spot in order to accomplish that, and with the Rangers having solid options if they want to send Holland to the minors, he needs a good spring. Brandon McCarthy didn't do his own chances any favors with two rough innings, so that helped, but Holland needs to shake off the rust and show some good progression in his next few outings. Lewis, Rich Harden and Scott Feldman are locks for the rotation, which means Holland, McCarthy, Tommy Hunter, Neftali Feliz (if not moved back to the bullpen), and maybe Matt Harrison (who is likely to shift to the 'pen) are fighting for two spots at the moment.• So why did I attend the Reds' "B" game in the morning? To see Homer Bailey make the start, and he looked just fine for this point in camp. He retired all six batters he faced in two innings, ranging between 90-93 mph with his fastball on a cold morning and showing good drop on his relatively new 85 mph splitter. That split-finger pitch is the key for him; he picked it up in the middle of last season, and it helped him go 6-1 with a 1.70 ERA over his final nine starts, with 53 strikeouts and 24 walks in 58 1/3 innings. It could wind up being what finally gets him over the hump permanently. Considering he's not being drafted in most ESPN standard leagues, there's good value potential here for the cost of a reserve-list pick.• Keith Law went to the Reds' "A" game to see Aroldis Chapman pitch, and based on his report, Chapman's slider looked more consistent than it was in his first throwing sessions in camp. The Reds were working with him to keep it from flattening out and looking more like a cutter, and it appears he's doing that. In my Top 100 prospects list, I put Chapman at No. 34 but noted that his early reports were positive, and that ranking might be deemed too low once we started seeing him in actual games. Given Keith's report, Chapman now would probably climb at least into my top 20.