Zach Britton has emerged as one of the best relief pitchers in baseball since converting to the bullpen full-time in 2014, registering a 1.82 ERA with a 1.04 WHIP, an 8.7 K/9 mark and 142 saves in that span, all of which makes him an enticing late-inning arm in free agency this offseason.
Below you will find a list of the latest news and rumors surrounding the southpaw.
Could Red Sox sign Britton to replace Kimbrel?
Dec. 22: The Red Sox are in the market for at least one high-leverage reliever, potentially two, and with Craig Kimbrel's asking price so high that he's since reportedly dropped it, Boston could pursue another avenue for the ninth inning. 
In a Sunday piece for the Boston Globe, Nick Cafardo outlines whyZach Britton could be a possible option. Boston, after all, was pursuing Britton ahead of the non-waiver Trade Deadline in July before he was eventually dealt to the Yankees. 
Britton knows the American League East, is comfortable pitching on a high-stakes stage and would likely be a more affordable than Kimbrel, who is supposedly seeking a five- to six-year deal in the $17 million to $19 million range. With Andrew Miller having signed with the Cardinals, Britton is the top left-handed reliever left on the free-agent market. As it stands, Christopher Johnson is the only lefty in Boston's bullpen. 
The Red Sox were one of just two clubs to exceed the Competitive Balance Tax threshold in 2018, and though they are in line to pass the $206 million CBT mark for '19, that won't necessarily stop ownership from spending this offseason, per Cafardo. Britton has expressed that he's open to a versatile role in which he pitches innings other than the ninth, though he's made it clear that he'd like to be paid like a closer. In Boston -- unless the Red Sox sign someone else soon, such as Adam Ottavino or Player Page for David Robertson, who Cafardo speculates as other targets -- Britton would be. 
How Miller's deal could impact Britton
Dec. 20: Zach Britton and Andrew Miller are the top two lefty relievers on the open market this offseason. One of them seems to have found a new home.
The St. Louis Cardinals are "closing in on" Miller, according to MLB Network insider Ken Rosenthal.

The Cards have been after a top-of-the-line southpaw relief ace and were eyeing both Britton and Miller all along, so landing the latter is big for them. Although the 33-year-old battled injuries in 2018, he has established himself as one of the premier late-inning arms in the sport, thanks to a 2.01 ERA and a 0.86 WHIP with a 14.2 K/9 rate since the start of 2014.

That leaves Britton as the No. 1 lefty reliever on the board, and MLB.com's Todd Zolecki speculates that the Phillies -- another club who has been chasing late-inning help, particularly from the left side -- could turn their attention toward Britton.

Britton is younger than Miller -- he'll be entering his age-30 season -- and has a similarly glowing track record. Over that same 2014-18 span, Britton has posted a 1.82 ERA and a 1.04 WHIP with 8.7 strikeouts per nine. Also like Miller, Britton had an injury plagued past season, missing the first portion while recovering from offseason surgery to repair his Achilles tendon.
Are Phillies cooling on Britton?
Dec. 15: The Phillies are pursuing a trade for Rangers left-hander Mike Minor, two sources told Scott Lauber of the Philadelphia Inquirer, but it's unclear where they would use him. Philadelphia is targeting starters and relievers, and Minor happens to be someone with recent experience in both roles. The left-hander was decidedly better as a reliever in 2017 than he was while pitching out of the rotation last season.
Lauber notes that if the Phils are looking at Minor as a reliever, it could indicate the club is "cooling" on left-handed relievers Andrew Miller and Zach Britton. That said, Jeff Passan of Yahoo Sports reported Friday that the Phillies have continued to target Miller while engaging with Texas about a deal for Minor. Passan made no mention of Britton, so it's possible he is no longer a primary target for Philadelphia.

Of course, that doesn't mean the Phillies are definitely out on Britton, whom the club was said to be "very aggressive" in pursuing earlier this week, according to MLB Network insider Ken Rosenthal.
Even after acquiring relievers Juan Nicasio and James Pazos from the Mariners in last week's deal that also brought in infielder Jean Segura, the Phils have remained in the hunt for a top-end reliever. And they've been prominently linked to Britton for some time, in addition to Miller, Craig Kimbrel, and, to a lesser degree, Player Page for David Robertson. 
Those acquisitions could also position the Phils to trade relievers Pat Neshek and/or Tommy Hunter to help acquire pieces they need elsewhere, which would only become more apparent should they sign a top reliever.
With owner John Middleton saying the club is prepared to spend aggressively and with general manager Matt Klentak loosely suggesting interest in Machado and Bryce Harper, the team's needs in the bullpen haven't been as prominently illuminated. Phillies relievers last year were worth 4.1 WAR, per FanGraphs, and posted a 4.19 ERA, which ranked 11th and 18th, respectively. Fortifying their backend could be just as pivotal for the Phils as making the offensive upgrades they aspire to. 
Cardinals interested in Britton
Dec. 11: The Cardinals have made their intent to address their bullpen known. With their acquisition of Paul Goldschmidt filling their much-needed need for an impact, middle-of-the-order bat, the Cards are expected to shift their sights to the relief market, and Zach Britton could be an option, according to MLB Network insider Jon Heyman. 

MLB.com's Jenifer Langosch reported Tuesday that St. Louis continues to spend a significant amount of its time at the Winter Meetings surveying the free-agent and trade markets for relief help. She added, however, that there was not a sense that the club was likely to complete that pursuit before departing.
Langosch writes that the club's pursuit has been established at a more "foundational level -- determining which relievers other teams would entertain trading, as well as what potential acquisition costs might be."
Cardinals relievers last year posted a 0.5 fWAR, the sixth-lowest in the Majors, and toyed with multiple players in multiple roles, with former starter Bud Norris pitching the ninth inning most of the season. The club signed Greg Holland to a one-year, $14 million deal during Spring Training only to release him in August after a tumultuous stretch in which he posted a 7.92 ERA over 32 outings.