Will Lincecum ever return to old self?

Before Game 4, one player said it would be a mistake to underestimate Tim Lincecum.

“He’s actually smarter than he gets credit for,” the player said. “He knows how to pitch.”

The player defending Lincecum was not a teammate but an opponent — infielder Skip Schumaker of the Cardinals.

Alas, once Lincecum took the mound, there was no escaping the jarring reality that the 2012 Timmy is not the 2010 Timmy, and might never be again.

Fans, reporters, teammates, opponents — we all enjoy watching Lincecum so much, we’ve been in a season-long denial, thinking he eventually would snap out of it.

But as Lincecum said after allowing four runs in 4 2/3 innings in the Giants’ 8-3 loss to the Cardinals in Game 4 of the NLCS on Thursday night, he has shown only “flashes” of who he once was.

He did it at various points in the regular season, did it while pitching 8 1/3 innings of relief in his first three postseason games. But when his team needed him most, he couldn’t do it against the Cardinals.

And so the Giants trail the National League Championship Series, three games to one. They are a good team, yes, but not nearly the team they were in ’10, when they combined dominant starting pitching with a powerful if flawed offense to win the World Series.

These Giants have gotten quality starts from right-handers Ryan Vogelsong and Matt Cain in the NLCS but poor ones from Lincecum and left-hander Madison Bumgarner. They’ve also scored just 15 runs in four games, with their best hitter, Buster Posey, getting almost nothing to hit and going 2-for-14 with three walks.

Oh, there still is hope for the Giants: Righty Lance Lynn, the Cardinals’ Game 5 starter, is not exactly a lock to pitch well after lasting only 3 2/3 innings in the series opener. A Giants win on Friday night, and the teams will return to San Francisco, with Vogelsong and Cain set for Games 6 and 7, the latter if necessary.

For that to happen, left-hander Barry Zito first must give the Giants a chance Friday night — and he actually beat the Cardinals in St. Louis on Aug. 7, allowing only two solo homers by Allen Craig in 6 2/3 innings. That game became a milestone of sorts, marking the beginning of 12 straight victories for the Giants with Zito on the mound.

Here are the numbers on Zito, though, that matter most: Left-handed hitters batted .209 against him in the regular season, right-handed hitters .281. And the Cardinals are a predominantly right-handed-hitting team.

The Giants, of course, never expected to rely so heavily on Zito. And if Timmy was the old Timmy, the series already might look entirely different.

“That’s obviously been the hardest part,” Lincecum said. “I’ve shown flashes of what I can do, or what I think I should be doing. But what it comes down to, it’s not about what I’ve done. I’ve got to figure out a way to do it differently now, get my outs.

“That’s the frustrating part. I’ve always been able to transition on the run and not necessarily worry about that. For me not to make that adjustment on the run is hard.”

He got into an immediate hole Thursday night, allowing the first three hitters to reach, then falling behind, 2-0. Manager Bruce Bochy repeated afterward what Giants pitching coach Dave Righetti said during the FOX broadcast: Lincecum, working exclusively out of the stretch, reliever-style, was “cutting off” his delivery, pointing his foot toward the third-base dugout and throwing across his body.

Righetti said that Lincecum later corrected the mechanical flaw, opening up his delivery and at one point retiring eight straight hitters. But Lincecum again found trouble in the fifth, allowing a booming double by Matt Carpenter after falling behind in the count, 2-0, then RBI singles by Matt Holliday and Yadier Molina.

“It just looked to me like his command isn’t quite as sharp as when I’ve faced him before,” Holliday said. “He’s still a very difficult at-bat. But he left some pitches over the middle of the plate, which he hadn’t done, in my experience, very often.”

Actually, Lincecum’s command and control were issues throughout the regular season. He produced the fourth-best strikeout rate in the NL, but also had the second-highest walk rate and 13th-highest home-run rate. His numbers — 10-15 with a 5.18 ERA — were about what you’d expect of a fifth starter, not an ace.

Thursday night’s outing, then, was not atypical.

“There was no lack of confidence in any of my pitches or (lack of) conviction in ’em,” Lincecum said. “They just weren’t hitting the spots that I needed ’em to.”

To think, this is a pitcher who won the 2008 and ’09 National League Cy Young awards, a pitcher who excelled in the 2010 World Series — but a pitcher who, judging from any number of objective measures, is regressing at an alarming rate.

Lincecum could have signed an extension worth more than $100 million last offseason; instead, he settled for a two-year, $40.5 million deal through 2013. He might not care as much as some about the money. But he cares deeply about his craft.

Not surprisingly, he said he was upset with himself Thursday night.

“It’s extremely disappointing,” Lincecum said. “You find it in yourself to pick your team up in a situation like this. But when you don’t go and do it, it’s that much harder to fall.”

He has fallen — hard.

Harder than most of us would have ever imagined.

Harder than most of us want to believe.