SAN FRANCISCO -- The Giants literally can defend their optimism regarding the upcoming season.
Newly acquired center fielder Denard Span should complement catcher Buster Posey, second baseman Joe Panik and Gold Glove-winning shortstop Brandon Crawford to strengthen San Francisco up the middle, traditionally regarded as the figurative backbone of any efficient Major League defense.
Giants manager Bruce Bochy, who issues superlatives only when they're deserved, sensed that excellence lies within the club's defensive range.
Bochy, who's approaching his 22nd season as a big league manager, expressed this sentiment during the Giants' introduction of Span at last Friday's news conference. Asked whether he has steered another club that possesses as much potential up the middle as this year's, Bochy responded, "No, I can't."
Bochy added, "If we play to our capabilities, I think we have a chance to be one of the best defensive teams in baseball."

The Giants already have entrenched themselves among baseball's best afield. They led the National League in defense last year, according to FanGraphs.com's advanced metrics. Moreover, they've ranked fifth or higher under the same index in six of the past seven seasons -- coinciding with the end of their stretch of four consecutive losing records (2005-08) and the start of their ascent to three World Series championships.
Not only did Crawford brighten this offseason by becoming the Giants' first Gold Glove winner since shortstop Omar Vizquel in 2006, but Posey, first baseman Brandon Belt and third baseman Matt Duffy also were named finalists for the award.
The Giants believe adding Span and moving incumbent center fielder Angel Pagan to left will help make their defense an active force, Span, a Gold Glove finalist in 2013 and 2014, is renowned for snaring difficult fly balls by getting good jumps and taking step-saving, accurate routes. He has recorded the highest range factor (putouts plus assists divided by the number of games played) among active outfielders and ranked among his league's top three center fielders in putouts four times between 2010-14.

On the other end of San Francisco's up-the-middle continuum is Posey, named catcher on the all-Fielding Bible team in The Bill James Handbook 2016. It's widely accepted that one of Posey's primary defensive attributes is his skill at occasionally prompting an extra called strike by framing borderline pitches. Statistically, Posey sparkled by throwing out 36 percent of baserunners attempting to steal, 8 percent above the NL average, and ranking second in the NL with a .998 fielding percentage.