In an October increasingly consumed by the bullpens, make sure to pay close attention to the pair of arms who will be starting Tuesday's Game 3 of the American League Championship Series in Houston, if only for the differences in style, background and approach.
That's because Dallas Keuchel is a durable soft-tossing lefty ground-ball machine, one who has been in Houston so long that when he debuted in 2012, the Astros were in the National League and wore brick-red-and-black uniforms. Meanwhile, Nathan Eovaldi is a flame-throwing righty, one with top-five starting-pitcher fastball velocity, who didn't pitch at all in '17 and has been with the Red Sox since July.
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One pitched in college and is a former AL Cy Young Award winner (Keuchel, 2015). The other was drafted out of high school (Eovaldi, '08), was once traded for Hanley Ramirez ('12) and injured his elbow so badly that he needed to have surgery before he could have Tommy John surgery, which was his second time undergoing the procedure ('16).
It's difficult to find two pitchers who are as diametrically opposed as these two are, but they do have one thing in common: In a few short weeks, they'll each be free agents, and they'll likely be among the top arms in a limited starting-pitching market. That means that when you tune in on Tuesday, you won't just be seeing two starters who should help swing a tied ALCS in one direction or the other; you'll be watching two pitchers who could end up being highly sought after on the open market beginning in November.
That's more than just speculation, too. Let's assume that Chris Sale, Cole Hamels, Madison Bumgarner, David Price and Clayton Kershaw, all with various opt-out clauses and team options, don't reach the free-agent market. (Kershaw is likely to opt out, but it's easy to see him reaching a new agreement with the Dodgers to remain anyway.)
If we look at the remaining free-agent starting-pitching options, two things become clear:
1. Arizona lefty Patrick Corbin will clearly be the top starter available. 
2. Everyone else is either entering their mid-to-late 30s (Carsten Sabathia, Charlie Morton, J.A. Happ, Anibal Sanchez, etc), didn't have strong platform years (Matt Harvey, Lance Lynn, Marco Estrada, Thomas Pomeranz, etc.) or is a unique case like Hyun-Jin Ryu, who was excellent this year for the Dodgers (1.97 ERA) yet hasn't thrown 150 innings since 2014.

To that end, we collected 24 free-agent starting options who faced at least 300 batters this year, a group that ranges in age from 28 to, yes, 45, as Bartolo Colon turned in May.
Here's how Tuesday night's starting duo ranked in a variety of important metrics.
Age: Eovaldi (28) second youngest, Keuchel (30) seventh youngest
Innings: Eovaldi (111) 15th, Keuchel (204 2/3) first
Strikeout rate: Eovaldi (22 percent) ninth, Keuchel (18 percent) 20th
Walk rate: Eovaldi (4 percent) third, Keuchel (7 percent) ninth
Four-seam fastball velocity: Eovaldi (97.5 mph) first, Keuchel (90.2 mph) 20th
Ground-ball rate: Eovaldi (46 percent) 12th, Keuchel (54 percent) second
Hard-hit rate: Eovaldi (35 percent) 13th, Keuchel (33 percent) eighth
Weighted On-Base Average (wOBA): Eovaldi (.293) seventh, Keuchel (.306) 12th
Expected Weighted On-Base Average (xwOBA): Eovaldi (.283) fifth, Keuchel (.289), seventh
(wOBA is an outcome metric similar to on-base percentage, except that more credit is given for more valuable hits, rather than treating each time on base equally. Expected wOBA is a Statcast™ metric that attempts to strip away ballpark and defense by focusing on the usual outcomes of the batted balls allowed, based on exit velocity and launch angle.)
Some of the differences there are clear, especially in velocity and in durability. (Though Eovaldi's total was kept down by the fact that he didn't make his 2018 debut until May 30, Keuchel reached 200 innings for the third time and has never been on the disabled list for anything more serious than a pinched nerve in his neck.)

Teams will account for all of that, clearly. But they'll also look at Eovaldi's status as the youngest starter available (he made his Major League debut at 21 for the 2011 Dodgers), and the trends that each of these two have shown to this point. 
For example, of the 189 pitchers who threw at least 100 innings in each of the past two seasons, no starter lost as much ground-ball rate as Keuchel did, dropping from 67 percent in 2017 to 54 percent in '18 -- though some of that can be explained by the fact that by leading all starters in '17, he had plenty of room to fall. That might not be so bad, except that he also dropped his strikeout rate from 21 percent to 18 percent, a top-10 drop among those 189 pitchers.
Eovaldi, meanwhile, was arguably the best starter traded this summer, depending on how you feel about Happ, thanks in part because the development of a new cut fastball (thrown 33 percent of the time, up from 8 percent in 2016) finally gave him a reliable complement to his relatively hittable four-seamer. By striking out 101 against only 20 walks, Eovaldi's 5.1 strikeout-to-walk ratio was a top-12 mark, between Corbin and Miles Mikolas. (He also didn't issue any walks in seven innings against the Yankees in Game 3 of the ALDS.) 

Interested teams aren't going to meaningfully change their evaluations based on what happens in one postseason game on Tuesday, but a sparkling performance against a good lineup would only serve to improve the cases of Eovaldi and Keuchel. 
Who might those interested teams be? Let's drop a pure speculation alert notice here and try to guess where the best fits might be.
Eovaldi
Best fit: Astros
What if Eovaldi's appearance in Game 3 isn't just about pushing the Red Sox closer to a title but is also about auditioning for his next club in person? The Astros will need rotation help if they lose Keuchel and Morton to free agency, and no team has proven themselves better at helping pitchers get the most out of their raw talent than Houston has.
Keuchel
Best fit: Yankees
Perhaps this is too obvious. Then again, it's clear that the Yankees need starters, with Happ, Sabathia and Lynn all reaching free agency; Masahiro Tanaka and Luis Severino can't do it alone. They're the clear front-runners for Corbin, and it's easy to see them being in on Keuchel as well, in part because Yankee Stadium is such an extreme hitter's park that someone who can keep the ball on the ground would be ideal. 
Other interested teams might include the Angels, Mariners, Reds, A's, D-backs, Rangers, White Sox and Brewers, but that's also somewhat just the tip of the iceberg here. After all, both Eovaldi and Keuchel are likely to be among the best free-agent starters available, behind Corbin. It's not going to be difficult to find interested suitors, and they'll all be laser-focused on every pitch on Tuesday night.