But is it actually true? In my opinion, it's impossible to reliably compare defense across eras but we can try. Using Baseball-Reference.com's Defensive WAR calculations (based on Sean Smith's Total Zone rating), we can at least see how dominant each player's defense was compared to their peers and see how it shakes out.
Brooks Robinson was a major league regular three years before Cal Ripken was born and was well on his way to his first Gold Glove when Cal was born in 1960, the first of 16 consecutive Gold Gloves that Robinson would win. While I'm certain that young Calvin Edwin was watching Orioles baseball all his life, he probably couldn't be a good judge or even recall much of those early years watching Brooks man the hot corner. Most of Cal's recollections are likely from the time his age hit double digits. Cal would have been 10 at the beginning of the 1971 season so we can start from there. Brooks played full time and at a high level from 1971-1975. In 1976 and 1977, he played sporadically and poorly. So for the sake of this post, I will assume Cal's memories of Brooks as a great player come mostly from the 5 season span from 1971-1975.
We will compare those 5 seasons to Adrian Beltre's most recent five seasons and see how they stack up.
Here are the top 10 third basemen in terms of Fielding Runs over the last 5 seasons as reported by Baseball-Reference.com:
Rk Player Rfield From To Age 1 Adrian Beltre 91 2008 2012 29-33 2 Evan Longoria 71 2008 2012 22-26 3 Scott Rolen 46 2008 2012 33-37 4 Placido Polanco 39 2008 2012 32-36 5 Jack Hannahan 36 2008 2012 28-32 6 Brett Lawrie 34 2011 2012 21-22 7 Ryan Zimmerman 34 2008 2012 23-27 8 Brandon Inge 28 2008 2012 31-35 9 Kevin Youkilis 27 2008 2012 29-33 10 Joe Crede 26 2008 2009 30-31By this measure, Beltre is the best and it's not even close. Even if you assume what Evan Longoria could've done if he'd been healthy this season, Beltre likely would beat him by 10 fielding runs. (By the way, how good is Brett Lawrie's glove? He's right in the middle of this list despite only 168 major league games under his belt.)
Here are the top 10 third basemen in term of Fielding Runs from the 5 season spanning 1971-1975:
Rk Player Rfield From To Age 1 Brooks Robinson 90 1971 1975 34-38 2 Graig Nettles 83 1971 1975 26-30 3 Mike Schmidt 38 1972 1975 22-25 4 Ron Cey 36 1971 1975 23-27 5 Buddy Bell 35 1972 1975 20-23 6 Darrell Evans 31 1971 1975 24-28 7 Aurelio Rodriguez 29 1971 1975 23-27 8 Eric Soderholm 26 1971 1975 22-26 9 Ken McMullen 16 1971 1975 29-33 10 Jerry Kenney 16 1971 1973 26-28It's Hall of Famer Robinson and Graig Nettles (who probably should be in the HoF) and nobody else. For the 5 season spans for each player:
Rfield rTZ Adrian Beltre 91 42 Brooks Robinson 90 83So it could be argued that Beltre was a wee bit better than Brooks over the two 5-year spans in question. Although, in terms of Total Zone, a Gold Glove caliber defender will score a TZ of 15 or more in a season. Brooks had 4 out of 5 of those seasons with a TZ of 15 or more. Beltre had none.
And as you my have noticed, these were Beltre's age 29-33 seasons; Robinson's were from his age 34-38 seasons. If we look at Robinson's 5 seasons from the same age span, he has an Rfield of 97 and three seasons over 15 rTZ, all over 20 and two over 30. Beltre's never had quite that kind of run.
Athletes get better as the years go by. It is very possible that if you took Beltre back to the 1960's he would have been Brooks' superior with the glove. But since we have to judge these things in the context of the eras they played, you have to compare their relative dominance to their peers. And given all that, I'd have to respectfully disagree with Cal. Adrian Beltre may be the best defensive third baseman of his generation but I don't think he's any match for Brooks Robinson.