Biddle was promoted to Triple-A Lehigh Valley on Tuesday, MLB.com's Todd Zolecki reports.

Biddle was once a highly touted prospect in the lower levels of the minors, but this was his third straight year at Double-A as the developmental process seemed to stall. A lefty with a big bender, Biddle is still just 23, but his 4.28 FIP and 57 strikeouts in 80.2 innings this year at Double-A show just how far he has fallen since the days when he routinely recorded more than a strikeout per inning. Biddle will likely get a shot at the big league level next season, but he now profiles as a No. 4 or No. 5 starter, and is therefore fairly uninteresting in most dynasty leagues.

Biddle told CSN Philadelphia that he is working on changing his approach this season. "I'm not trying to pick apart the plate too much," Biddle said. "I'm attacking hitters and being aggressive down in the zone and not pitching for strikeouts. I'm not judging my performances on how many strikeouts I have, but judging them by how many early groundballs I got."

Biddle's strikeout rate has dropped from 8.77 K/9 last season to 6.11 this season. He also has shaved nearly a walk off his BB/9 ratio, dropping from 4.82 last season to 3.9 this season. The walk rate is still too high, but at least Biddle is moving in the right direction now. Overall, he is 7-1 with a 3.62 ERA and a 47:30 K:BB ratio in 69.2 innings for Double-A Reading.

Biddle allowed one run on five hits over five innings in a win for Double-A Reading on Tuesday. He walked two and did not strike out a batter.

Biddle was returning to the rotation after having his last start skipped in order to work on his mechanics. The lefty is 4-1 with a 4.46 ERA and a 30:19 K:BB ratio in 40.1 innings this season.

Biddle was scratched from his start for Double-A Reading on Friday to work on his mechanics, the Phillies' official site reports.

Biddle walked five batters in his most recent start and now has walked 17 batters in 35.1 innings this season. He is scheduled to rejoin the rotation on Tuesday to make his next start.

Biddle, 23, tossed five shutout innings Saturday for Double-A Reading. The 6-foot-5 southpaw allowed just two hits, walked two batters and fanned four.

Biddle had a rough 2014, both mentally and physically. He posted a 4.58 ERA and 92:51 K:BB ratio in 94.1 innings, mostly at this same level. He battled quad and elbow injuries, and also took some time off to recharge mentally. 2015 will be a clean slate, and Biddle is off to an excellent start.

Biddle has been optioned to minor league camp.

He'll likely begin the season back at Double-A after struggling while repeating the level in 2014. If he proves to be healthy and effective, Biddle should be positioned to get a look at Triple-A by mid-season.

Manager Ryne Sandberg said Biddle (elbow) has stood out early on in camp, the Philadelphia Daily News reports. "[He's] really doing a good job," Sandberg said. "Every time he pitches and does sides, he has really good command. He's showing his pitches and seems to be really in control."

Control has been an issue for Biddle throughout his time in the minors. If he can command his pitches more consistently he can make a significant jump forward this season. Biddle was once considered the top prospect in the Phillies' system, but he has dropped out of many Top 10 lists after his struggles last season. He is completely healthy this spring after dealing with mild tendinitis in his elbow while pitching in the Venezuelan Winter League.