The Giants just added a 27-year-old left-hander with a 93 mph fastball and major-league success under his belt on an affordable contract until 2019. That left-hander, Matt Moore, hasn’t recorded the same ERA or strikeout rates he’d produced before his Tommy John surgery, but if you look under the hood, the stuff seems to be back.

That stuff, and that contract, made it worth the hefty price: 21-year-old right-handed pitcher Michael Santos, exciting young 19-year-old Bahamian shortstop Lucius Fox, and — most painful of all — 25-year-old major-league third baseman Matt Duffy. Dave Cameron will have more on the choice to include Duffy, but either way, it’s a price you pay for a pitcher you believe can serve at least as a middle-of-the-rotation guy. A price you pay if you believe Moore has his stuff back.

By ERA, Moore has been a bottom 25 pitcher over the last year-plus. Even FIP (18th-worst), xFIP (10th-worse), and SIERA (21st-worst) all suggest that Moore hasn’t been good. The strikeout- and walk-rate differential (K-BB%) hasn’t been amazing either (86th out of 124).

But we’re lumping in Moore’s terrible return last season with his merely mediocre work this year. And we’re ignoring that his stuff took a leap forward this year. The easiest thing to notice is that Moore’s fastball velocity is up a full tick in 2016. But that doesn’t sum it all up. The rest of his pieces are starting to click, too.

Let’s take a look at spin rates, which are the “process” stats for a pitcher’s stuff. Notice, in particular, Moore’s lower spin rate on the changeup. You want a lower spin rate on your changeup because that means more drop and more drop means more swings and misses.

Matt Moore Spin Rates Pitch 2015 2016 Four-Seamer 2350 2276 Change 1758 1547 Curve 2539 2407 Sinker 2245 2214 SOURCE: Statcast Higher = better for four-seamer, curve.

Lower = better for sinker, change.

Average spin rates for 4S (2226), CH (1750) and Curve (2300).

Moore has maintained the high spin rate on the four-seamer, which gives him ride on the fastball, while removing over 200 rpm from his changeup. That’s given him his drop back on his changeup. Actually, Moore is seeing the most drop on his change that he’s ever seen. It now tumbles a full six inches more than his four-seamer. That’s a top-10 number.

Movement differential off the fastball is one of the best markers for changeup quality, so it’s no surprise that Moore’s changeup has been good for 18% whiffs over his career and remains above average this year (14%). Add to that changeup a fastball that’s two ticks faster than the lefty average, and you’ve already got a one-two punch worthy of the middle of any rotation.

The curve was really the driving force behind a young Moore who once looked poised to join the top-30 pitchers in the league. From the table above, you can tell that the curve has lost some sizzle in terms of spin. The good news is that it’s recovered much of its old stuff in other ways.

Matt Moore’s Curve, Then and Now Curve Aspect 2012-2013 2014-2015 2016 Velocity 81.6 79.6 81.2 Horizontal Movement -2.8 -2.9 -3.2 Vertical Movement -3.0 -7.1 -6.0 Whiff % 12.9% 9.3% 12.1%

The curve is back.

How does this sum up and compare? It looks like we have a lefty with plus fastball velocity and two above-average secondary pitches. Among qualified pitchers, that sentence describes only Clayton Kershaw, David Price, Chris Sale, Cole Hamels, Francisco Liriano, and Moore this year.

Changeup whiff rate has the lowest correlation to overall strikeout rates, so sometimes pitchers like Moore don’t put up the whiff rates you’d expect from a guy with a plus changeup. But Moore now has two good pitches other than the fastball, and with $26 million dollars in team options over the next three years, he’s also affordable. You can see why the Giants ponied up.