Over the past half-decade, the San Francisco Giants have won three World Series championships, mainly by riding their pitching, starters and relievers. With minimal offense, the pitching staff needed to be excellent more often than not, and they usually responded with resounding results.

2015 has been a complete reversal for the Giants. Their offense is the catalyst of their success, and San Francisco is the only team in the National League with 1,000 hits. Their .328 on-base percentage is the best in the National League, while their .272 batting average and 466 runs scored are both second in the Senior Circuit, while a .413 slugging percentage is third.

While the offense has surged, pitching has become an issue for the Giants. The pitching staff that once picked up porous offensive performances is now relying on an offense to return the favor. They have not been awful, as the staff’s ERA and WHIP both rank in the top half of the National League, but they do seem to need a refresher.

The most prevalent spot in the bullpen, the one that grabs the most headlines is the closer’s role, and that role is one that may benefit from a change.

Santiago Casilla, the Giants’ current closer, has been the recipient of some mostly-unfair criticism over the past few years. From the start of the 2010 season to the end of the 2014 season, Casilla’s 2.10 ERA was the fourth-lowest in baseball among relievers with at least 200 innings pitched. He quieted a lot of the criticism with a sterling start to his season.

From the start of the year to the end of June, Casilla was dominant in the ninth inning, owning a 2.12 ERA, .229 opponent batting average, and 1.247 WHIP in his first 34 games of the year. He looked the part of ninth-inning lockdown man, and even made a case to be included on the All-Star roster.

But since the calendar turned to July, Casilla has turned as well, and that criticism has become warranted. His numbers have inflated, as he owns a 7.56 ERA, .378 average against, and 2.281 WHIP in his last 11 appearances.

Casilla’s numbers are a bit skewed by two particularly terrible appearances. On July 1st, Casilla allowed a three-run walkoff home run, with all three runs being charged to Casilla without recording an out. In his latest outing, on August 3rd, Casilla allowed two runs in two-thirds of an inning. In both instances, Casilla blew a save opportunity.

This could very well be a case of Casilla simply wearing down. Since joining the Giants ahead of the 2010 season, he’s thrown 316.2 regular season innings, which is 27th-most among big league relievers. Farther than that, when postseason innings are factored in, Casilla has thrown 335.2 frames, the 21st-most among relievers.

In general, relievers are known to have pretty short shelf lives. The Giants should consider themselves quite lucky to have had a core of relievers that have been as dominant for as long as they have. But it may be time to consider some changes in the bullpen, namely in the ninth inning.

The proper replacement may just be the man that’s been deemed “closer of the future”, Hunter Strickland.

The problems that plagued Strickland in last year’s postseason are a distant memory. After allowing six home runs in 8.1 innings and 34 batters faced, Strickland put his problems behind him and is pitching with renewed confidence this season.

He started the year in Triple-A Sacramento, taking on the closer’s role. In 15 games and 21.2 innings, Strickland posted a 1.66 ERA, 0.785 WHIP, and 8.33 strikeouts-per-walk ratio. He earned his call-up on May 21st, and he has stuck in the Giants’ bullpen since.

With the big league squad, mostly as a seventh or eighth-inning setup man, Strickland owns a 1.86 ERA, 0.966 WHIP, and 5.5 K/BB rate. Combined between both levels, Strickland’s numbers are outstanding. In 50.2 innings, he has a 1.78 ERA, .206 opponent average, 0.888 WHIP, and 6.6 K/BB rate.

He has shown new weapons, fastballs with two different types of movement (two-seam movement in to right-handers, and cut movement away from right-handers) and a slider he has begun to throw more often.

Another big point is Strickland’s favor is that he has experience closing out games. In 2013 with High-A San Jose, Strickland was nine-for-nine in save opportunities. In 2014 with Double-A Richmond, he was 11-for-11 closing out ballgames. In 2015 before the call-up, Strickland was a perfect five-for-five in save chances.

Minor leagues are obviously a different world than the big leagues, but Strickland has done well in his limited chances in the bigs as well. He earned his first career save in his seventh game in 2014, pitching a perfect 13th inning against the Los Angeles Dodgers to close out a wild game. In NLDS game two, Strickland earned the save in the 18-inning marathon game, allowing just a walk in his inning of work.

Obviously, Casilla hasn’t been the only reliever who has struggled through problems this year. Sergio Romo has had to throw 9.2 scoreless innings since the All-Star Break to work his ERA down to a more respectable 3.79. Jeremy Affeldt is still attempting to whittle down his 5.88 ERA.

Some issues could be resolved by giving Strickland a bigger role in the bullpen, and transversely, reducing Casilla’s load. Putting less pressure on Casilla, possibly by making him an eighth-inning reliever, could make him more effective.

With the Giants within striking distance in the NL West, the bullpen may just need a shakeup to settle things down.