Statistics confirm that Romo, San Francisco's right-handed setup specialist, deserves to be ranked among the most elite relievers in club history.
Composing this fantasy list requires including the franchise's three most prolific closers, Robb Nen, Rod Beck and Brian Wilson; the Giants' top two relievers in all-time appearances, Gary Lavelle and Greg Minton; and Stu Miller, a member of the inaugural West Coast team of 1958 whose changeup was legendary.
The combination of past glories and present circumstances gives this group relevance. Nen is the only one who ended his career with the Giants. Romo, 32, will be eligible for free agency after this season. He strongly prefers to remain a Giant, but the club might balk at approaching the $9 million he'll earn this year.
Romo admitted Thursday that his impending free agency is "hard to ignore," adding, "I still feel that I can give more, produce more and be a good example of what it is to play Giants baseball."
Romo is being handled with care this spring, due to his injury history. During Thursday's initial workout for pitchers and catchers, he played catch on flat ground while other pitchers threw off mounds.
"Same as [Denard] Span or [Joe] Panik on the position-player side," Giants manager Bruce Bochy said, referring to projected regulars who are said to be healthy but are coming off injury-wracked seasons.
Durability wouldn't appear to be an issue with Romo, who appeared in a career-high 70 games last season. Mostly, though, determining a reliever's value through that or any other number is risky. A high percentage of inherited runners scoring makes ERAs meaningless. Save totals can be inflated by closing games with relatively pressure-free three-run leads.
However, modern metrics offer alternatives.
Consider Win Probability Added (WPA), which measures the degree to which a reliever influences his team's chances for victory, typically by analyzing his data regarding allowing baserunners or stranding inherited runners. Romo ranks third in this category for Giants relievers, behind Nen and Wilson, since 1901.
Then there's RE24, which is similar to WPA but deals more specifically with runs allowed. Calculations for RE24, which date back only to 1974, heavily favor Romo, who tops the Giants' list. Nen's in second place, while current Giants closer Santiago Casilla occupies third.
For some observers, the relative complexity and anonymity of such figures invalidate them. But Romo's backers consider him a legitimate candidate for the theoretical ultimate Giants bullpen.
"He's in the conversation, big-time," Giants pitching coach Dave Righetti said. "It's not just the closers with the big stats."
One of those closers, Nen, happens to be a huge fan of Romo's. They met early in Romo's career when Nen served as a part-time instructor, a role he still holds.
"He's a guy who's very confident in what he does, and he knows what he's doing," Nen said. "He doesn't need anybody to tell him how to pitch. He's not afraid to challenge hitters, and that's what makes him such a great pitcher."
Romo treasured such praise from Nen, whom he deeply admires.
"He had a fire under him," Romo said. "He was amazing. He could tell you what was coming, and it wasn't that you couldn't hit it. He just was going to will you to not hit it."
The mention of Romo's slider, which has helped him amass 465 strikeouts in 409 Major League innings and compile a 0.946 WHIP since 2008, prompted a reciprocal remark from Nen: "Oh, my God. They know it's coming and they can't hit it."
Romo was a 2013 All-Star, recorded the final out of the '12 World Series by striking out dangerous Tigers slugger Miguel Cabrera and has clinched a spot on the Giants' Wall of Fame after he retires. Making an impact in the game was what he envisioned despite being selected in the 28th round of the 2005 Draft.
"Coaches will mention players, ex-teammates of theirs, and I'm like, 'Wow, I haven't heard that name in forever,'" Romo said. "It's almost like you forget these people and their contributions to the game. I figured I didn't want to be like that. I wanted to be part of something cool, something that's going to be remembered."