A PTBNL is going the other way.
Let's take a look at the newest Redbird.
John Axford is a former dominant late inning reliever - averaging 66 innings, 35 saves, a 2.19 ERA, 81 K, 26 BB, and 50 hits between 2010 and 2011 in Milwaukee. His WHIP was a quite manageable 1.162, while is K:BB was over 3 with a K/9 over 11!
The last two years, with Milwaukee basically out of contention by the end of June, he has averaged 62 innings pitched with 18 saves, a 4.57 ERA, 74 K, 31 BB, and 62 hits in Milwaukee. His WHIP jumped to a much more scary 1.492, while his K:BB was under 2.5 and his K/9 dropped to 10.7. This year, his K/9 is down under 9 and his WHIP is over 1.5. He is trending in the wrong direction there.
Let's look deeper.
While Axford's FIPs have gone from 2.13 and 2.41 in his two great years to 4.06 last year and 4.75 this year; his xFIP (remember, the only difference there is taking the amount of HR allowed and regressing it to the mean) was 2.79 and 2.85 in his two great years to 3.29 last year and 3.66 this year. That shows that maybe not everything has changed for Axford.
What about his batted ball data? He's allowed nearly 20% of his fly balls for homers the last two years - that should change in the HR depleted Busch Stadium. However, Axford has allowed line drives on nearly 1/4 of the balls hit over the last two years combined after having been below 20% for two straight years in 2010 and 2011.
Lastly, we can look at his pitches to get a better idea about Axford's arm.
In 2010-2011, Axford was throwing 67% fastballs at 96 mph. He also had a workable slider and curve at 13% (coming in at 85 mph) and 19% (coming it at 81.5 mph), respectively.
This season, Axford has thrown 63% fastballs at 95.79 mph. It looks like 11 (1% of his total pitches) pitches have been thrown as "sinkers." My guess is that some of his fastballs moved a little more as they are basically the same speed. He's throwing his slider at 83.4 mph now and nearly 15% of the time. His curve is coming in around 79 mph and 21% of the time.
I really see no reason that Axford couldn't regain at least a mix of his 2011-2012 form. There's no reason he should be pitching as badly as he is in 2013 at just 30 years of age. He only has 263 1/3 innings on his arm in the majors and another 239 2/3 in the minors.
Lastly, Axford could be a mainstay in the bullpen for a while. He is set to earn arbitration in 2014-2016, so he won't be a free agent until 2017 - if the Cardinals choose to retain him.