Left-hander Antonio Bastardo fits into that group. He showed plenty of promise his first few seasons in the big leagues, but any success he had took a hit this past season when Major League Baseball suspended him 50 games for using a performance-enhancing substance.
Bastardo will have to prove himself in 2014, when he will be asked to anchor the back end of the Phils' bullpen alongside closer Jonathan Papelbon and setup man Mike Adams, who could miss the beginning of the season following right shoulder surgery.
Bastardo is pitching well in winter ball in the Dominican Republic. He is 1-1 with an 0.66 ERA in 14 appearances with Gigantes del Ciabo. In 13 2/3 innings, he has allowed two runs (one earned run) on six hits and four walks, with 23 strikeouts.
The reliever was 3-2 with a 2.32 ERA in 48 appearances with the Phillies last season before being suspended. He is 11-8 with a 3.12 ERA in 177 appearances the past three seasons.
Bastardo has held batters to a .187 average in that span, which is the second-best mark among qualifying left-handed relievers. Only Reds closer Aroldis Chapman has been better. Chapman has held opponents to a .151 average.
Bastardo's problem has been walks. He has averaged 4.3 per nine innings the past three seasons.
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.