Senzel, 22, had been at the team's player development complex in Goodyear, Ariz., since May 16 -- after his symptoms subsided. He's spent the past few days playing games with players at the extended spring camp.
"He played well and saw the ball well," Graupe said. "He looked back to normal. Now it's about him going back to game action at his level again and re-progressing again."
Senzel, who is ranked as the organization's No. 1 prospect by MLB Pipeline and No. 6 overall, was placed on Louisville's 7-day disabled list on May 9. He hasn't played for the Bats since May 3, when he was removed from the game after feeling dizzy following one plate appearance.
Graupe said that Senzel would resume playing games at both second base and third base.
Senzel is batting .271/.351/.459 in 22 games with three home runs and seven RBIs this season.
Iglesias close to returning
Reds closer Raisel Iglesias, who was placed on the 10-day DL Wednesday because of a strained left biceps in his non-pitching arm, met the club in Phoenix and was at Chase Field ahead of the series opener vs. the D-backs. Iglesias is scheduled to throw a side bullpen session on Tuesday.
"I feel fine right now. I'm ready to go. I don't feel any pain anymore," Iglesias said via translator Julio Morillo.
Back on May 9 vs. the Mets, Iglesias had to reach high to catch a ball and appeared to be in discomfort. But he wasn't exactly sure how he originally hurt his arm. The last time he pitched, May 19 vs. the Cubs, he blew a save and ended a scoreless streak of 9 1/3 innings over 10 appearances by giving up two earned runs and three hits.
"That game with the Cubs, it was bothering me a little bit," Iglesias said. "But we're players and we play through pain sometimes. I pitched that game and it was fine. But the next day when I threw, I couldn't get any extension. It was getting worse and worse and I told the team."
In 20 appearances, Iglesias has a 2.08 ERA with 0.92 WHIP and eight saves.
Reliever Austin Brice, who went on the DL the same day as Iglesias with a mid-back strain, also rejoined the team at Chase Field and threw a side bullpen session on Monday.
Because their DL stints were retroactive to May 20, both Iglesias and Brice could be activated on Wednesday.
"It's not cast in stone that they will, but it's certainly a possibility," Reds interim manager Jim Riggleman said.
Barnhart taking to two-hole
For his fifth straight start, Reds catcher Tucker Barnhart was in the second spot of the lineup -- his first-ever start there during his career. Barnhart entered Monday 7-for-20 and had hits in each of the previous four games from the No. 2 spot.
When Riggleman had Barnhart while managing at Double-A Pensacola, he wasn't known for his hitting at all.
"Watching what he's done the last few years, especially last year, he's really become a legitimate Major League hitter," Riggleman said. "You can hit him second, you can hit him sixth or seventh.
"[In] '12 he was only 21, he was such a catch-and-throw guy, block the ball. He was outstanding. He was just projected to be -- not by me, it was my first year and I didn't know him like some other people knew him in the organization -- but he was projected as he'd catch in the big leagues as a backup catcher, he'll be that good [defensively]. He's taken it to another level with the way he's swung the bat."