Can we replace three quarters of the roster with better players? No? Oh. I think the Bucs may have a problem, then.
All kidding aside, there's one thing the Bucs can do to get better this season: get their defensive players to execute the scheme. Players have to just do what they're told, and stop trying to do more than their job. Cornerbacks have to drop to their spots, and not next to their spots. Linebackers need to run down the field in coverage, not stop halfway letting someone get behind them. And everyone needs to stay in his gap in run defense, instead of jumping out of it at the last second on a whim.
The team's already thrown Leonard Johnson under the bus, although he may retain his starting job. Extra competition at multiple spots will certainly help -- or it can't make things worse, anyway.
The Bucs are coming off a bye week. They've had just a little bit of extra time to get the details correct. To drill it into their players' heads that they can win, as long as they just execute the scheme. This is not rocket science. It's a scheme that works -- just look at the Dallas Cowboys, or the Carolina Panthers last year. But for it it to work, players just have to show up and do their jobs.