Some people could say no. Adding Robinson Cano, Logan Morrison, and Corey Hart to a team that already had Felix Hernandez and Hisashi Iwakuma is huge. Prospect Taijuan Walker is very promising. The Mariners look like they have a good mixture of clubhouse chemistry and new additions, something that you could argue that the Blue Jays didn't have. One could also point to the Marlins clubhouse chemistry, who already had Hanley Ramirez, Logan Morrison, and Giancarlo Stanton, while adding the likes of Jose Reyes and Mark Buehrle. The Marlins previously had some pieces, but when they went to add more, the team crumbled. It's hard to know how well Cano, Morrison, and Hart will fit into the Mariners' chemistry.
Another similarity between the Mariners and the Blue Jays and Marlins is the managing situation. The Mariners have hired a new manager, Lloyd McClendon. The Blue Jays and Marlins hired new managers John Gibbons and Ozzie Guillen, respectively. The Marlins and Blue Jays didn't know what to expect from their new managers, forcing a change upon not only their new additions, but the returners as well. The same thing could and might happen with Lloyd McClendon and the Seattle Mariners.
From a statistical standpoint, the Mariners improved their team. But, I cannot see them contending in the very competitive American League West as of right now. Most people agree that the Rangers and Athletics have better rosters than the Seattle Mariners. I would listen to an argument that said the Angels have a better roster than the Mariners. However, the Mariners roster may not be complete. They are continuing to be competitive in the rest of the dwindling offseason, becoming interested in the remaining top tier free agents, such as Japanese ace Masahiro Tanaka.
As of right now, I believe that the Mariners will be the next disappointment team after "winning" the previous offseason. They could continue to add pieces, but their current roster coupled with the "playoff standards" in that tough division does not impress me overwhelmingly. However, I would not be surprised to see the Mariners be very improved. I could see them in the running for a Wild Card, but until they get the players on the field, it is truly unknown how well the Mariners will fare in the 2014 season.