SAN FRANCISCO – After one of the Giants’ first games of the season, Bob Melvin sat in his office in the middle of Petco Park and raved about the potential All-Star season ahead for their second baseman.

Things didn’t work out that way for Thairo Estrada. He was activated from the injured list before Monday’s series opener against the White Sox. But it may not be a coincidence that the 28-year-old from Bejuma, Venezuela, will tell you that was the last time he was at full health.

“First of all, I’m very happy to be back,” Estrada said through team interpreter Erwin Higueros. “At the moment, I’m 100% fine. I’m not in any pain. I feel good.”

Before a left wrist injury sidelined him for three weeks, Estrada had a batting average of .216/.249/.353 — an OPS of .601 — and was on pace for career lows in nearly every offensive category. He’s been 5% better than the league’s average hitter over the past three seasons, but this year he’s been one of the league’s worst with an OPS+ of 71 (100 is the average).

“This year hasn’t been his best, but we feel like he’s back to full health now and has had a good rehab,” manager Bob Melvin said. “Hopefully that’s a nice addition to the lineup.”

In five games with Triple-A Sacramento, Estrada recorded nine hits in 21 at-bats (a .429 average), including a home run and a double on Sunday.

The Giants’ lineup has scored more than four runs only once in the last 10 games when batting as a team around the Mendoza Line, and it’s been even worse when runners have been in scoring position. Estrada admitted, “It’s hard to say that with my arrival we’re just going to start scoring runs. It’s not easy.”

Estrada’s replacements were not part of the solution. Since landing on the IL on July 26, the Giants’ second basemen have been the fifth-worst offensive group in the major leagues, with a batting average of .217/.252/.360 and a league-low walk rate of 3.2%.

Left-handed hitter Brett Wisely was relegated to Triple-A in a corresponding move, leaving the Giants with no options for the team’s roster but with a more reliable defender in Casey Schmitt to replace the middle infield positions.

“Right now (Schmitt) probably only brings a little bit more,” Melvin said. “Against left-handers, we can probably still use a right-hander.”

Since the beginning of August, Wisely was 4-for-25 with a .392 OPS.

“I think Wise just needed to get to the bat a couple of times,” Melvin said. “He lost a little confidence, maybe he applied a little too much pressure. But he’s been really good for us at times this year. … It’s in there. He’s just having a little tough time right now.”