Aug 14, 2016; Toronto, Ontario, CAN; Toronto Blue Jays relief pitcher Jason Grilli (37) celebrates after getting the third out during the eighth inning in a game against the Houston Astros at Rogers Centre. The Toronto Blue Jays won 9-2. Mandatory Credit: Nick Turchiaro-USA TODAY Sports

When Aaron Sanchez graduated from the bullpen to the top of the Blue Jays rotation to begin the 2016 season, it helped propel the Jays’ starting pitching staff to one of the best in the major leagues. It also left a glaring need for a stop-gap relief pitcher that could get the ball to Roberto Osuna in the ninth.

An army of pitchers were given a shot at handling the crucial eighth inning duties. Brett Cecil, Drew Storen, Gavin Floyd, Joe Biagini, and Jesse Chavez have all been called upon to pitch the eighth in games where Osuna has recorded a save this season. While the mission was accomplished most of the time, it typically came with a level of uncertainty, messiness, and a lack of punch that has become so important in today’s game where most contenders have heavy reinforcements for their starter after the sixth inning.

On May 31, Toronto sent 21-year-old pitching prospect Sean Ratcliffe — who has since been released — to the Atlanta Braves for a 39-year-old relief pitcher with a 5.29 ERA and a $3.5 million salary. It was the best trade the Blue Jays made all season.

Since heading over to his favourite childhood team, the former All-Star has filled a void in the bullpen and completely shut down the eighth inning. While the pitching has been stellar, his “Tiger Woods fist pumps”, pro-Canada Twitter account (@GrillCheese49), and terrifyingly-intense persona on the mound have made him a loveable fan favourite in two short months. A change of scenery has been the most-discussed reason for Grilli’s dramatic performance increase, but the credit should really go to his execution of pitches and game plan with catcher Russell Martin.

Knocking down an ERA of 5.29 in 17 innings with Atlanta to 1.69 in 26 and two-thirds innings with Toronto can’t just be chalked up to a “fresh start”. In fact, one of the major factors in Grilli’s turnaround has been the use of his slider. In his 21 appearances with the Braves, he threw the slider 32.4% of the time, compared to 39% in 28 games with the Blue Jays. Not only is he throwing the slider more often, but it has been more effective as a complimentary pitch to his fastball and using the breaking pitch more often has translated into a much higher ground ball percentage. 38.8% of balls in play have been on the ground as compared to just 18.6% when he was in the National League, according to FanGraphs.

While his slider been extremely effective in generating weaker contact and keeping hitters off balance, his fastball has also made significant improvements. At 39-years-old, it is rather uncommon for a pitcher to find an extra gear towards the second half of a season, but Grilli is the farthest thing from common. His fastball has added milage throughout the course of the year.

In Atlanta, his average fastball was 91.8 MPH and has been bumped up by almost one mile per hour with the Blue Jays at 92.6. Maybe the boisterous 40,000-plus crowds at the Rogers Centre have something to do with the extra juice he has been getting on his four-seamer. The right-hander did not average 94-plus MPH on his fastball in any of his appearances with the Braves in 2016, but hit the 94.16 mark in his Blue Jays debut at home against the Yankees. He has reached the 94 MPH average plateau on three other outings with Toronto and his velocity increased in each month of the season, before a slight dip in August.

Another factor that has translated into tremendous American League success is his execution around the strike zone. He continues to get ahead of hitters and take control of each at-bat as a 67.4 first pitch strike percentage is a career high and is far better than the 50.6% career low he posted in his first half with Atlanta. The early strikes have obviously significantly lowered his walk rates, but the impressive part is that he has not suffered from more contact against by being around the strike zone more often. 17.5% of pitches in the zone are creating swings-and-misses from the opposition — another career high that is well above his 9.6% with the Braves.

Grilli’s arrival in Toronto could not have come at a better time and he continues to improve as the season goes on, despite being at the tail end of his career, making the $3 million team option for 2017 look more and more appealing. If the Blue Jays can find anything close to the rejuvenation that Grilli has gone through with newcomer Joaquin Benoit, who is in a similar situation, it will make for a deep bullpen as the season stretches into crunch time in September.