On April 30, the Los Angeles Angels had a record of 8-15 and sat 9.5 games behind the first-place Texas Rangers. Today, the Angels are 40-33. They are now only 4.5 games behind the Rangers, and tied for the second wild card with the Tampa Bay Rays. Much of the focus for the Angels success in May and June has been on rookie sensation Mike Trout, Albert Pujols‘ re-found stroke, and the overall play of Mark Trumbo.

But don’t overlook the Angels’ bullpen. After a poor start, Angels relievers have been hugely important to the team’s revived play. And it wasn’t just the addition of Ernesto Frieri in early May that turned things around for the Angels’ relief corps.

In April, Angels relievers were 0-6 with three saves, a 1.52 K/BB, and a 4.42 FIP. Jordan Walden, then the closer, was a mess, with a 17.4 % walk rate and a 6.05 FIP. Middle relievers Jason Isringhausen and Hisanori Takahashi also lagged, with 7.43 FIP and 5.09 FIP, respectively. Scott Downs, the veteran left-hander, was the bright spot, with a 2.00 K/BB, a 0.86 WHIP, and a 100% LOB.

After Frieri arrived, things began to settle down. He shared closer duties with Downs in May. Neither allowed an earned run in the month. Walden’s move to middle relief paid off, as he raised his K/BB to 2.00 and lowered his FIP to 2.57 in 12+ innings of work. Isringhausen and Takahashi also pitched well in May, posting 2.06 FIP and 3.26 FIP, respectively. David Pauley and David Carpenter, who pitched poorly in April, continued to lag in May.

In 21 games and 55.1 innings pitched in June, the Angels’ bullpen sports the lowest team ERA in the majors at 1.95, although they are eighth in FIP at 3.20. The relievers are 4-0 with eight saves, a .226 batting average against, and a 0.49 HR/9, nearly half of home run rate as they posted in April. Frieri still hasn’t allowed an earned run since joining the Angels. Downs allowed his first of the season on June 10. As a group, the bullpen has pitched 18.1 consecutive scoreless innings over the last six games.

But there are trouble signs. (Of course there are trouble signs. Nobody’s perfect).

LaTroy Hawkins came off the disabled list in early June and added 13.2 innings to the bullpen’s efforts this month. And while his 0.66 ERA looks spiffy, it’s belied by a 3.50 FIP. His strikeout rate of 3.95 K/9 is significantly below his career average of 5.96, and his walk rate of 3.95 BB/9 is significantly above his career rate of 2.96. Not surprisingly, his first pitch strike rate (47.4%) and his swinging-strike rate (4.0%), are at the lowest of his career.

Isringhausen, at 39, is holding batters to a .175 average with a .204 BABIP, numbers very likely to rise as the season wears on. His walk rate is in line with his career average but his strikeouts are down. Like Hawkins, his swinging-strike rate (6.6%) is the lowest of his career.

Frieri’s been untouchable but that may very well change. His 14.97 K/9 is the fifth highest among all qualified relievers since 2002 and nearly 3.00 K/9 higher than his career average. His 4.81 BB/9 is in line with his career marks and, therefore, unlikely to drop. Both his batting average against (.116) and his BABIP (.204) are well below his career norms.

Through Monday’s action, the Angels’ bullpen has pitched only 189 innings, the third least in the majors. Only the Giants and Phillies relievers have pitched fewer innings. Obviously, Angels’ starters have gone deep into games the first three months of the season, weathering the 15-day disabled list stint by Jered Weaver. But Dan Haren and Ervin Santana haven’t pitched well consistently. If that trend continues, manager Mike Scioscia is likely to rely more heavily on the ‘pen down the stretch. It remains to be seen whether the relievers will continue to pitch as well with a heavier work load.

In March, many crowned the Angels as the likely American League pennant winner. In April, many were tossing their pre-season picks out the window. Now, more than a third into the season, the Angels are playing as well as expected and are in the hunt for a postseason berth. The bullpen has been an important part of the team’s turnaround. It will need to maintain its current level of effectiveness to keep the Angels in the hunt for October.