After 15 years of operating fantasy games, Sandbox.com has announced via a letter on its site (and e-mailed to users) that this season will be its last.

“The fantasy sports industry has changed significantly in the past few years and as Sandbox.com’s popularity declined, it became increasingly more difficult for us to offer you the kind of fantasy sports experience you deserve,” the letter states. “This is a decision that we did not make lightly, and we know that many of you will be disappointed. We’re disappointed too.”

Sandbox says it will allow all current seasons in football, college football, golf and NASCAR to complete and that it will officially close on January 7. The site is “recommending” that users move their leagues to CBSSports.com.

“They have been in the industry for over a decade and know how fantasy is done,” the letter says, regarding CBS. “To help with this transition, we are working with CBSSports.com to determine the best options for you to migrate your leagues over to their games.”

(This is a somewhat interesting partnership, considering that Sandbox has operated for the past few years under the ownership of NBC Sports, coming as part of the All Star Sports deal that also included Rotoworld.com.)

Sandbox.com opened with free games back in the mid-’90s — and was actually the first place this writer ever played — before switching to pay in the early 2000s. According to Compete.com, unique-visitor totals have hovered mostly near 20,000 a month in this final year.

In the latest sign of fantasy sports’ ability to swim in the mainstream, Compete.com released last month some stats on the Web habits of fantasy players.

Compete drew results from a panel of “more than 2 million” Internet users based in the United States for the month of September, compiling numbers on daily reach, search habits and time spent on various fantasy sites.

The fantasy sports subdomain on Yahoo! and the games subdomain ESPN.com, respectively, came out as the clear top two in unique visitors, each more than doubling the next ranked URL. Worthy of note, however, is that NFL.com’s fantasy area came in third, even if you were to combine the results for each of the three ranked CBS Sports subdomains (football, baseball and college football).

Streak.espn.go.com led the way in average stay, checking in at nearly 5 minutes more than No. 2 fantasy.nfl.com. That URL, of course, takes surfers to ESPN’s Beat the Streak game, which won a Fantasy Sports Trade Association award for 2009. FleaFlicker.com and fantasy.foxsports.com followed in that category.

RTSports.com led the way in visits per person for the month at 20.56. Only two other sites beat Compete.com’s overall tally for the category (14.71): baseball.cbssports.com and myfantasyleague.com.

Other data points drawn into focus in the Compete.com release were:

– Unique visitor numbers don’t tell the entire story. Fantasysports.yahoo.com was the top site for UVs in September (6,115,530) but “attention” increased 130 percent — still not bad, while fantasy.nfl.com attention increase by 370 percent. Perhaps the increased focus on video at fantasy.nfl.com is behind its relatively higher attention.

– For search, ESPN was the clear winner for September. It captured three of the top five search-share positions: “espn” was the number one keyword sending traffic to the fantasy category, “espn fantasy football” was the number two keyword and “espn.com” was number four.

– Fantasy players drop off as the season wanes. Baseball.cbssports.com, which reached its season high in April of 516,761 UVs, was down to 347,416 in September with attention down (44 percent) and visits per person down (25 percent) from August. It’s likely that many players lose interest as they move out of contention and content related to the next fantasy season emerges (football, hockey and basketball). Wise brands should track these trends and use the insights to drive campaign creative and media buying.

More results can be found in the table below …

Say this for fantasy football players: When they get inspired by a movie, they stick with it. At least, that’s my takeaway from looking over the top 200 team names list that CBSSports.com released on Thursday.

The group of most common titles is full of predictables such as “Bulldogs” (for ugly owners), “Cowboys” (for bandwagon riders), “Raiders” (for those who don’t particularly care about football) and “Shockers” (comprising only graduates of Wichita State, I have to assume).

No. 1 on the list, though, is “Mean Machine,” harkening back, of course, to the 1974 football classic The Longest Yard. (I refuse to acknowledge the role of the more recent Adam Sandler turd or 2007’s overlooked The Longest Yard Sale, “the low-budget movie with big-budget depth.”)

Scroll just a little ways down the list, and you’ll find The Karate Kid-inspired “Cobra Kai” at No. 22, followed at No. 29 by “McLovin” of Superbad fame.

The full list can be seen via the first link in this article. The top 20 goes like this:

1. Mean Machine
2. Bulldogs
3. Cowboys
4. Da’ Bears
5. Steel Curtain
6. Shockers
7. Warriors
8. G-Men
9. Raiders
10.
11. Big Dog
12. Eagles
13. Sharks
14. Steelers
15. Show me your TDs
16. Wildcats
17. Gang Green
18. Prime Time
19. Big Blue
20. Rookies

Any time you see a list of the top 10 anything, you know that a fair bit of subjectivity went into the selections and you probably take the list with a grain of salt.

That said, you won’t find many more trusted resources for “all things Web” than Mashable.com, with its 3 million-plus unique visitors a month and more than 2 million Twitter followers. So when that site comes out with its “Top 10 Fantasy Football Sites to Help You Win,” it’s at least worth passing along.

The article doesn’t specifically say that the list represents a ranking, but the whole numbering thing seems to indicate as much. Here are the sites that Mashable’s Miranda Lin likes best, with a snippet of her comments for each …

1. Footballguys.com – “Having up-to-the-minute breaking news is the life-blood of any fantasy footballer, and Football Guys’ network of writers and inside sources is one of the best in the business, producing an “avalanche of news” that will keep you ahead of the game.”

2. RotoWorld.com – “The speed and quality of their newswire is second only to Football Guys and their ‘On Demand Draft Guide’ ($14.99) produces an easily printable document filled with player profiles and stat projections, ADP reports, rookie rankings, depth charts and injury reports that are updated in real-time and tailored to your league settings.”

3. The Huddle — “The Huddle has it all: Cheatsheets, player profiles and rankings, mock drafts, game predictions, free agent reports, start/bench advice and stat trackers. … But what really sets The Huddle apart are its forums.”

4. Fantasy Sharks — “This is the only site on this list that is 100% free — and it doesn’t give up anything in quality.”

5. FFChamps.com — “The site’s crown jewel is the FFC Performance Index, an in-season ranking and projection system that calculates which of your players will have the best outing.”

6. Football Docs — “Apparently the Football Docs’ advanced degrees in engineering have also given them an inside track on fantasy football trends, draft tactics, lineup decision-making, and player rankings and projections.”

7. CBSSports.com — “Although it’s not as organized or as user-friendly as some of the other sites, it’s hard to argue with the quality of CBS Sports’ product.”

8. Pro Football Reference — “Doug Drinen has put together a super-organized, easy-to-navigate collection of football statistics that allows users to search any aspect of a team or player’s performance throughout history.”

9. Draft Sharks — “With a sleek-looking interface that provides custom tailored cheatsheets (called MVP Boards), weekly player rankings, newsy and gossipy articles, personalized trade advice and in-season strength of season updates, Draft Sharks believes it can ‘out-analyze other websites.’”

10. ESPN.com — “In addition to the usual news and analysis from its stable of experts, including five-time Fantasy Sports Writers Association (FSWA) award-winner Matt Berry (aka ‘The Talented Mr. Roto’), ESPN has begun to offer a variety of services across different media platforms.”