Well, it is official: Adam LaRoche is a D-back.

After rumors swirled for a day or two, the deal was announced Friday afternoon, with the veteran first baseman signing a one-year deal with an option for a second.

It should work quite well for the D-backs on many levels. LaRoche is a good defender at first base and a good left-handed bat to put alongside Miguel Montero in a middle part of the lineup that was pretty right-handed before (Jackson, Upton, Reynolds).

Furthermore, he’s a good-power, good-on-base player and with those five above-mentioned players, that should be a formidable group. With solid seasons from Stephen Drew and Kelly Johnson at the top, the D-backs are looking at some offensive lineup improvement over 2009.

For what it’s worth, LaRoche has done very well against teams in the NL West. Check out his numbers against the D-backs’ chief rivals in what would amount to just less than a full season: 137 games, 32 home runs, 40 doubles, 92 RBI, 80 runs, a .301 average, .360 on-base and .584 slugging (.944 OPS). Those are excellent numbers.

Here he is against each team specifically:

Team ———————- AVG/OBP/SLG – HR – 2B – RBI – R
San Diego Padres ——- .322/.377/.618 – 12 – 9 – 27 — 27
Los Angeles Dodgers— .259/.331/.578 – 11 – 4 – 30 — 18
San Francisco Giants—- .336/.387/.628 – 5 – 16 – 23 — 18
Colorado Rockies———- .280/.350/.495 – 4 – 11 – 12 – 17

LaRoche is pretty famously a second-half player. For whatever reason, he’s just always gotten better and better as the season as gone on (which, one supposes, is always a better reputation to have than being a hot starter/cold finisher). So even if LaRoche doesn’t explode out of the gate, don’t then presume something is wrong; the history shows he’ll likely blow up pretty well in the second half.

As an aside, the LaRoche move allows the organization to be patient with young first baseman Brandon Allen, who can go into Spring Training working with hitting coach Jack Howell and the D-backs staff on his specific offensive goals, without the added pressure of fighting for a starting spot.