Five free agent relievers Red Sox could pursue from World Series teams

Hector Rondon

Hector Rondon has declined a bit from his peak years as the closer for the Chicago Cubs but he’s been a solid late-inning option in Houston’s bullpen the last two seasons.

The 31-year old posted a 3.71 ERA and 1.25 WHIP in 60 2/3 innings for the Astros this season. While those are solid numbers for a middle reliever, there are some concerns.

The most startling difference was Rondon’s drastic drop in strikeout rate to a career-low 7.1 K/9. Rondon has struck out a batter per inning over his career and had a K/9 above 10.0 in each of the previous three years.

There wasn’t a noticeable decline in velocity to explain the lack of strikeouts. Rondon averaged 96.9 mph with his four-seam fastball, which is a bit below last year’s velocity but a tick above his career rate, per FanGraphs.

He threw his four-seam fastball only 45.9% of the time, his lowest usage since 2015. Rondon started throwing his sinker more often, a pitch he mostly abandoned over the last three years. This may explain why his swinging-strike percentage fell to a career-low 9.8% with Rondon aiming to induce more ground ball outs with the sinker at the expense of strikeouts.

Rondon was effective early in his career throwing the sinker but the pitch may be less effective for him in the launch-angle era. He matched his career-high with 10 home runs allowed.

A change in approach to improve his strikeout rate and limit the long ball could lead to a bounce-back year for Rondon, making him a potential bargain.