Gio Gonzalez’s grimace took up the entire lower portion of his face — a scowl so wide and so dour, it seemed to expand to the tips of his newly grown mop of hair. Head hung low, he walked slowly off the mound as he made his way to the Nationals’ dugout, barking at himself for allowing the Mets to load the bases in the seventh.

Don’t get us wrong, Gonzalez got the win Wednesday night in the Nationals’ 7-1 victory at Citi Field. Felipe Rivero got the last two outs of the inning and the Mets didn’t score. And, up until the seventh, Gonzalez did what he’s done a whole lot of this season — he dominated. And he continued to march to the tune of his storyline: The pitcher once known for his sky-high emotions is now, this year, known for his ice-cold composure.

Although Gonzalez is more poised on the mound, the person hasn’t changed, and the emotional aspect — part of his competitiveness, really — lives on in the lefty. In many ways, the balance appears to have made him even more of a dangerous foe for anyone foolish enough to think that Gonzalez is a garden-variety No. 3 pitcher.

His liberal use of his two-seam fastball and curveball last night had the Mets tied up in various uncomfortable knots. He struck out both Curtis Granderson and David Wright in the first inning — setting Granderson up with the fastball and an 88-mph two-seamer before finally ringing him up on a 77-mph curve. Wright struck out on his curve twice — first in that first inning, and then looking in the sixth to end the inning.

Gonzalez pitched 6 1⁄3 innings, allowing one run on five hits, with a walk and five strikeouts. He threw 94 pitches, 62 for strikes, and cruised until Yoenis Cespedes’ soft leadoff single in the seventh. He allowed two more singles before getting pulled for Rivero after having allowed only two other hits up until that inning.

Of course, one of the most mind-bending facts about Gonzalez as we see him right now is that he’s often eclipsed by his teammates on the rotation — it’s fairly difficult to compete for the limelight with Max Scherzer, who’s struck out 30 batters in his last two starts, or Stephen Strasburg, no longer a wunderkind, but still pretty wonderful.

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After last night’s performance, he’s 3-1 with a 1.86 ERA and a WHIP of 1.09. In terms of ERA, it’s the best start of his nine-year major-league career (he had a 2.22 ERA over eight starts in 2012).

Entering yesterday, he ranked sixth in the NL in ERA and homers allowed per nine innings (.43). Though he allowed a home run to Cespedes in the fourth, little else of Gonzalez’s feats this season took a hit last night.

And that, for someone like him, is certainly something to smile (widely) about.